just how restrictive are the stock TPI engine components?



just how restrictive are the stock TPI engine components?

Postby grumpyvette » April 6th, 2009, 11:25 am

I get this question frequently so let me point out a few things

viewtopic.php?f=32&t=601

viewtopic.php?f=55&t=1052&hilit=pro+flo+edelbrock

viewtopic.php?f=55&t=858

http://www.compcams.com/Community/Artic ... 1737510521

viewtopic.php?f=55&t=431&p=48733#p48733

http://chevythunder.com/

https://www.youtube.com/watch?v=S_ni39iwAys

http://mysite.verizon.net/vzezeqah/site ... ystems.pdf

viewtopic.php?f=69&t=433

http://www.eecis.udel.edu/~davis/z28/wi ... 21105.html

IF you check around on the site theres a good deal more cylinder head , port, and cam, flow data and info on how to match components, if youve got questions please post, as IVE got only about 10% of the info on my hard drives posted currently

the first thing you need to do is step back and decide ,anytime you plan engine upgrades you need to take the SYSTEM approach, as no one component alone will function to its full potential unless matched to other components that are designed to operate at the same rpm, flow and power rates, if your going to swap to far better heads, a larger duration cam, high efficiency & low restriction scavenging exhaust and higher numerically rear gearing , higher compression, possibly larger displacement and a low restriction exhaust so that a huge flow rate on the intake flow increase can be effectively used, or if your basically adding JUST an intake to add some upper rpm flow to a basically stock engine where you don,t intend to do other major mods, the difference in what your trying to do and the results your likely to see will dictate a totally different approach. a simple intake change alone won,t produce outstanding results, its the old (weakest link in the chain deal) even if the intake flow is potentially far better, if the heads and cam won,t allow the intake to flow up to its full potential you won,t see a big change, and too get a noticeable change, all three components need to be upgraded


use this calculator
http://www.rbracing-rsr.com/runnertorquecalc.html

it should open your eyes, the stock TPI runner is optomised for 3400rpm on a 350, with its 1.7 sq inch cross section,swap to, for example the larger FIRST TPI, it jumps to 4800rpm, with its un ported 2.4 sq inch cross section, that alone is worth almost 100 hp is both engines made the same peak 400 ft lbs of torque at there optimum rpm peaks, but your likely to find the larger ports more efficient.
that's one reason the MINI-ram advertises it can make 100 more hp than a TPI, its not that the mini-ram, FIRST,or STEALTHRAM intakes that great, its that THEY ALL allow the engine to breath far higher into the engines upper rpm range where the stock GM TPI has become exceptionally restrictive to flow compared too,the mini-ram, FIRST,or STEALTHRAM intake


when you combine head flow with intake flow in most cases those measurements were done on the individual components on a flow bench, if the heads flow 200cfm at .500 lift and the intake flows 190cfm that in no way indicates that you'll reach similar numbers with all the components bolted together.
remember your valve is only at full lift (AND THAT'S WELL UNDER .500 with a stock cam) for a very few degrees in the 720 degree repeat cycle, so your very unlikely to even approach those flow numbers, with the stock cam that has about a 195 intake duration, at .050 lift, that's about 27% of the total cycle even if the cam was INSTANTLY fully open and held open for the full 27% of the time, but the truth is its open for a great deal less time at peak flow.

the stock TPI head flow is in the 190cfm-200cfm range, that matches the stock head flow rates,and the stock cam lift.
read thru the posted links theres a good deal of useful info, but keep in mind its a balanced system your after designed to operate in a known rpm range and displacement, its almost always better to increase flow rates and engine displacement, but most components must match, a killer cam designed to operate at 6700rpm won,t work well with heads that effectively become a restriction at 5500rpm, an intake designed to maximize power at 5500rpm should be matched to a cam and heads designed for a similar rpm band and a drive train designed or allow the engine to opperate in that same rpm band 90% of the time.
larger displacements, higher compression ratios and carefully matched components can produce an engine that has impressive torque, excellent durrability and a car thats fun to drive at BOTH the track and on the street!
peak horsepowers nice for bragging but having instantly available massive torque in your cars intended rpm band, matching your trans and gear ratios, is far nicer on the street, and almost as fast or just as fast on the track. keep in mind your cars drive train ,trans stall speed and rear gearing must match the power curve.

Ive tested a bunch of IMPROVE TPI REPLACEMENT style intakes on my cars, one of the best is the ported HOLLEY STEALTH RAM, but theres CLEARANCE ISSUES on some cars as its 10" tall and a corvette for example has only 9" of hood clearance so a CUSTOM PLENUM or a HOOD SCOOP is MANDATORY TO RUN ONE on a corvette for example !


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the stock TPI intake flow rarely reaches 196cfm

http://dtcc.cz28.com/flow/index.htm

IF your keeping the stock heads and cam , or even just the stock heads and a decent upgraded cam you'll want to keep the basic engine configuration similar to the TPI, in the rpm range and power curve configuration, but you want to add flow to boost the hp, the SUPER RAM, or the FIRST TPI, but keep in mind the results you see won,t reflect the intakes true potential without better heads and a cam with more duration that will allow the heads, intake and cam to flow the necessary air to produce significantly higher power levels.

viewtopic.php?f=55&t=823

both those intakes are designed to maximize torque in about the 1800rpm-5800rpm band(depends on porting, heads,displacement, compression, head flow, exhaust scavenging etc.

they will maintain the basic rpm band but at higher flow rates,thus youll have noticably more power without getting into the short block too much,

the mini-ram and stealth ram are both designed to operate a a noticably higher rpm band (about the 3500rpm-6700rpm band) so better heads and higher (3.54:1-3.73:1)rear gear ratios, larger durration cams (usually in the 220-min-to at least 239-245 dur max at .050 lift) range and higher compression ratios become almost mandatory if you want to maximize those intake manifolds potential.

http://stealthram.com/flowcomparison.html
(keep in mind in some cases the intakes are ported and in some cases they were right out of the box)

Here's some flow figures, right off the manufactures sites in many cases. Keep in mind the concept of the chains weakest link. It does ABSOLUTELY no good to match a base or runners on a TPI intake that flows 250cfm if the other part flows 200cfm. You'll still only flow 200cfm. The HOLLEY STEALTH RAM FLOWS at 275cfm out of the box,(minor port clean-up work) and can easily reach 300cfm with minor port work. The stock TPI has a hard time flowing 230cfm even with minor port work. Look here. Most of this info is right off the Accel, Holley, Edelbrock, and TPIS sites. Add a little math and the results become much clearer!!!

Intake......runner length .... port in...... out
Stock GM Base----- 6.375"------------- 1.47"------- 1.96x1.20
TPIS base------------6.125"------------- 1.75"------- 2.09x1.28
Accel base-----------6.125"------------- 1.75"---------2.09x1.28
Holley base--------- 6.000" ------------ 2.30”-------- 1.90x1.23 (2.337 sq inches)

Runners
Stock TPI-------- 7.250"------1.470" round(1.70 sq inches)
SLP -------------- 6.625"------1.600" round (2.01 sq inches)
Accel LTR------- 6.625"------1.615" round (2.05 sq inches)
TPiS-------------- 7.625"------1.660" round (2.168 sq inches)
Mini ram --------3.500”
stock MRII with 1204 (AFR 195) ports, 58MM - 265 cfm
stock MRII with 1206 (AFR 220) ports, 58MM - 281 cfm
MRII clean-up, 1206 ports, 58MM - 292 cfm
MRII cut, weld, port, etc, 58MM - 321 cfm
LT1 ----------3.000”

Runners (measured individually)
Stock........................................................................................................................................203.17 cfm
ACCEL.....................................................................................................................................242.02 cfm
Extrude/ACCEL........................................................................................................................275.83 cfm
Super Ram................................................................................................................................289.18 cfm
Intake manifold with 3/8 inch radiused inlet .............................................................................222.45 cfm
Holley stealth ram ………..........................................................................................................275.00 cfm


Stock intake manifold with runner
Stock.........................................................................................................................................198.72 cfm
ACCEL......................................................................................................................................213.52 cfm
Extrude/ACCEL.........................................................................................................................217.11 cfm
Super Ram.................................................................................................................................220.67 cfm
Holley stealth ram ….................................................................................................................275.00 cfm
ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet.....................................................251.51 cfm
ACCEL Hi-Flow intake manifold with runner Stock...................................................................215.83 cfm
ACCEL......................................................................................................................................232.53 cfm
Extrude/ACCEL.........................................................................................................................243.21 cfm
Super Ram.................................................................................................................................240.24 cfm
Extrude-Honed ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet.............................275.83 cfm
Extrude-Honed ACCEL Hi-Flow intake manifold with ACCEL runner.......................................266.94 cfm
Edelbrock Performer RPM manifold (Stock)...............................................................................286.51 cfm
Edelbrock Victor Jr....................................................................................................................275.24 cfm


Runner Length


Stock TPI manifold ...................8” ...............runners 11.25”............... cylinder head 6”.............total 25.25”
Accel super ram manifold........ 8”................runners 7.00”............... cylinder head 6”............ total 21.00”
Holley stealth ram manifold .....6.26” ................................................. cylinder head 6”............ total 12.26”
Edelbrock performer RPM ...........................runners 6.00”................ cylinder head 6”............ total 12.00”
Edelbrock Victor Jr .......................................runners 5.50”................ cylinder head 6”............ total 11.50”




Now playing with the figure in the calculators below, what you'll find is that if your using a 350 size engine as a guide, the tpi runner length is ideal for peak tq 3427rpm and 2700-4000rpm for peak hp.

The Accel Super Ram is ideal for peak tq at 4032rpm and 3300rpm-4800rpm for peak hp.

Holley's Stealth Ram runner length is ideal at 4700 for peak tq and 5618rpm to 6282rpm for peak hp.

The TPIS Mini Ram and LT1 intakes are ideal for peak tq at about 5200rpm and 7244rpm to 8101rpm for peak hp.

By hp peak, in the above lists, I'M REFERRING TO THE RPM RANGE WHERE combination of cross sectional area MATCHED TO THE plenum to INTAKE valve distance WHERE THE internal AIRFLOW HARMONICS TEND TO INCREASE THE CYLINDER FILLING EFFICIENCY (WHERE THE INTAKE WILL TEND TO PULL THE MOST HP). Now KEEP FIRMLY IN MIND the engines tend to enter valve float and get close to engine red line by 6300-6700rpm depending on your combo. After running all the available combos, I've found a HOLLEY STEALTH RAM has been EXTREMELY EFFECTIVE on several engines tested. CURRENTLY THE STEALTH RAM SEEMS TO
BE THE CHOICE, ESPECIALLY IF MATCHED TO GOOD CYLINDER HEADS AND THE CORRECT
CAM.

bytor wrote:Came across this info while doing some research and thought I'd share.

http://www.hobracing.com/tech/tpi_flow.asp
TPI Intakes and runners

The following airflow tests were performed on the University of Northwestern Ohio's SuperFlow SF600 Flow Bench. All CFM values are corrected for airflow at 28 inches of water. Injector flow rates are flowed at 43.5 PSI on an injector flow bench using test fluid with same density as gasoline.

AirFlow

Stock TPI/LT1 48mm Throttle Body w/o airfoil -- 783.0 cfm

Stock TPI/LT1 48mm Throttle Body w/ airfoil -- 821.9 cfm

TPI/LT1 52mm Throttle Body w/o airfoil -- 848.9 cfm

TPI/LT1 52mm Throttle Body w/ airfoil -- 898.8 cfm

Stock 98 Camaro 3800 II Throttle Body -- 554.3 cfm

Stock TPI Bosch MAF sensor w/ screens -- 517.8 cfm

Stock TPI Bosch MAF sensor w/o screens -- 658.4 cfm

Stock 87 GN 3.8L Turbo AC MAF sensor w/ screen -- 584.2 cfm

Stock 86 2.8L AC 5-wire MAF sensor w/ screen -- 576.2 cfm

Stock 96-up AC 3100 V6 MAF sensor w/ screen -- 616.4 cfm

Stock 96-up AC 3100 V6 MAF sensor w/o screen -- 670.7 cfm

Stock 94-up LT1 MAF Sensor w/o screen -- 719.0 cfm

Stock 85-87 Firebird TPI airbox mid piece -- 499.3 cfm

Stock 4.3/5.0/5.7 2bbl TBI complete -- 574.1 cfm (dry)

Stock 4.3/5.0/5.7 2bbl TBI w/o injectors -- 584.7 cfm

Stock 3800 vin L throttle body w/ screen -- 419.1 cfm

Stock 3800 vin L throttle body w/o screen -- 444.8 cfm

4bbl MPFI Holley Throttle Body -- 1287.6 cfm

Another source sent in these flow numbers

Flow and HP ratings for Throttle-bodies:

Flow (cfm) Max. NA HP
Stock 668 300
Stock w/airfoil 710 350
52MM w/airfoil 835 400
54MM (AS&M) 900 450
58MM 1050 500


TPI Intakes and runners flow rates

Stock intake manifold with runner
Stock....................198.72 cfm
ACCEL................213.52 cfm
Extrude/ACCEL....217.11 cfm
Super Ram............220.67 cfm

the stock TPI has a hard time flowing 230cfm even with minor port work, look here
most of this info is right off the accel,holley,edelbrock, and TPIS sites, add a little math and the results become much clearer!!!

Intake....... length ....... port in -- out
Stock GM Base--- 6.375"------ 1.47"- 1.96x1.2
TPiS base------ -6.125"------ 1.75"- 2.09x1.28
Accel base----- -6.125"------ 1.75"- 2.09x1.28
Holley base------- 6” runner 2.3”- 1.9”x 1.23 (2.337 sq inches)
Runners
Stock TPI----- -- 7.250"------1.470" round(1.70 sq inchs)
SLP ----------- - 6.625"------1.600" round (2.01 sq inchs)
Accel LTR------- 6.625"------1.615" round (2.05 sq inchs)
TPiS----------- 7.625"------1.660" round (2.168 sq inchs)
Mini ram -----3.5”
LT1 ----------3”

Runners (measured individually)
Stock....................203.17 cfm
ACCEL................242.02 cfm
Extrude/ACCEL...275.83 cfm
Super Ram............289.18 cfm
Intake manifold with 3/8 inch radiused intlet.............................222.45 cfm
Holley stealth ram ………..275cfm

Stock intake manifold with runner
Stock....................198.72 cfm
ACCEL................213.52 cfm
Extrude/ACCEL....217.11 cfm
Super Ram............220.67 cfm
Holley stealth ram …..275cfm

ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet.........251.51 cfm

ACCEL Hi-Flow intake manifold with runner
Stock....................215.83 cfm
ACCEL................232.53 cfm
Extrude/ACCEL....243.21 cfm
Super Ram............240.24 cfm

Extrude-Honed ACCEL Hi-Flow intake manifold with 3/8 inch radiused inlet ...............275.83 cfm
Extrude-Honed ACCEL Hi-Flow intake manifold with ACCEL runner ..............266.94 cfm
Edelbrock Performer RPM manifold (Stock)..........286.51 cfm
Edelbrock Victor Jr. ............275.24 cfm

HOLLEY STEALTH RAM
the HOLLEY STEALTH RAM FLOWS at 275cfm out of the box, and has the potential when matched to the correct heads and cam to totally out flow most other intakes available,can easily reach 300cfm with minor port work and costs much less
Stock…………………………… 275cfm
Ported…………………………..300cfm

Runner lengths
Stock tpi manifold 8” runners 11.25”, cylinder head 6” total 25.25”
Accel super ram manifold 8” runners 7” cylinder head 6” total 21”
Holley stealth ram manifold 6.26” ” cylinder head 6” total 12.26”
Edelbrock performer RPM runners 6” ” cylinder head 6” total 12”
Edelbrock vic jr , runner length 5.5” ” ” cylinder head 6” total 11.5”



Also interesting TPI mods. Not so sure I agree with the one on bumping up the initial timing.
http://www.hobracing.com/tech/tpi_mods.asp


Basic TPI modifications
Friday, May 23, 2014





Basic TPI Mods: by DEBBIES87

There are a few basic mods that should be done to any TPI car, I call these "entry-level" modifications.

1) Cut the air box open without letting air in the engine without going through the air filter & remove the additional plastic piece below the air box to get more air into the engine.

2) Modify the mass air sensor; remove the screens, & and if your brave cut down the fins.

3) Port the plenum (upper intake). There are two small ridges sticking up in the entry-behind the throttle body, remove these. The throttle body openings are already 52mm, so don't go crazy when porting.

4) While the plenum is off for porting, it is now a good time to get a adjustable fuel pressure regulator & a MAT sensor relocater kit. The Adj. FPR will aid in tuning, and the new MAT sensor will improve throttle response as well. The new LT1 style MAT sensor is placed in the air box instead of the plenum, this allows it to read cooler air and advance the timing accordingly.

5) Advance the base timing to 12-13 degrees. Note: the harmonic balancers on these cars tend to drift with age, adjust timing to where the car still starts good and doesn't detonate.

6) If legal in your area, gut the catalytic converter and remove the smog pump belt (85-87), or run a shorter serpentine belt to bypass the pump (88-92); you will need to remove the smog pump on the 88-92's to reroute the belt properly. Check local smog laws first.

7) On automatic cars, adjust T.V. cable (throttle valve cable), so that the car shifts out between 4200-4500 RPM under wide open throttle. TPI motor power drops off drastically after 4500-4700 RPM, they peak at about 4200-4400 RPM. No need to over-rev these motors.

8) Bypass fan relay to make fans come on manually, or install aftermarket relay to turn on fans sooner.

All together these mods should make the car perform like it should have from the factory, gains should be between .6-.9 tenths of a second from these modifications.




T.V




The intake ports on the STEALTHRAM as it comes from HOLLEY. It fits the Felpro #1205 gasket port size.


viewtopic.php?f=55&t=431&p=530#p530

the stock cam is designed for maximium cylinder fill efficiency at no more than 5500rpm


viewtopic.php?f=52&t=133

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the stock stamped rockers are rarely at a full 1.5:1 ratio, in fact 1.45:1 is comon when carefully tested with a dial indicator

viewtopic.php?f=52&t=126

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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: just how restrictive are the stock TPI engine components

Postby grumpyvette » October 22nd, 2010, 3:45 pm

increasing power is in large part the result of increasing the amount of air/fuel mix you can efficiently pack into and burn in the cylinders and the number of power strokes per second that the engine can produce in its effective power range.
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youll want to read these threads

viewtopic.php?f=52&t=462&st=0&sk=t&sd=a&hilit=porting+help

viewtopic.php?f=52&t=333&p=8319&hilit=porting+help#p8319

viewtopic.php?f=69&t=1060&p=2031#p2031

viewtopic.php?f=52&t=322

http://www.cis.udel.edu/~davis/z28/buil ... e/porting/

http://www.gmtips.com/3rd-degree/dox/ti ... t/port.htm

http://www.cis.udel.edu/~davis/z28/buildup/plenum/

viewtopic.php?f=52&t=1070

viewtopic.php?f=52&t=480

viewtopic.php?f=52&t=796

viewtopic.php?f=71&t=741&p=1048#p1048

heres a few pictures that were posted on line of the EDELBROCK TPI BASE that has larger runners than the stock TPI base, keep in mind that having a killer set of high flow runners or a ported plenum won,t result in much of a air flow gain with a restrictive stock base and even with a high flow runners, and base and plenum the stock heads won,t show much flow improvement, ...you'll require both better flowing intake components and a set of much better cylinder heads to increase the flow rates, but even then, if you don,t use a cam with enough duration and lift high flow components can,t fill the cylinders and build more power unless the valves are held open far enough and long enough to allow a significant improvement in the combos air flow potential
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KEEP IN MIND THERE ARE OTHER SOURCES FOR HIGH FLOW TPI STYLE BASES, LIKE THE FIRST TPI CLONE
RUNNERS AND BASE SHOWN BELOW
http://www.firstfuelinjection.com

http://firstfuelinjection.com/PDRM1966.JPG
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: just how restrictive are the stock TPI engine components

Postby grumpyvette » November 1st, 2010, 11:39 am

the one major factor most of you are ignoring is that all the intake manifolds are designed to operate at different rpm ranges , and REQUIRE a cam and cylinder heads that will flow the MATCHING CFM FLOW RATES and in the intended RPM BAND , and obviously the engines displacement, and compression ratio must be compatible with the cam timing and lift and if the compression and cam used does not exactly match the intakes rpm range the intake will produce far lower numbers!


EXAMPLE
my PORTED STEALTH RAM produced far better power with both a CRANE 119661 and CROWER 00471 than with cams that worked correctly with the PORTED TPI with high flow runners, because the HSR is designed to operate at a HIGHER AVERAGE RPM BAND than the stock type TPI design intake.
READ THRU THIS
viewtopic.php?f=55&t=1745&p=4378&hilit=+stealth#p4378

the one major factor most of you are ignoring is that all the intake manifolds are designed to operate at different rpm ranges and if the compression ratio fails to be correctly matched to the cam and if the cam used does not exactly match the intakes rpm range the intake will produce far lower numbers!
then your also ignoring the fact that once the intake flow exceeds the heads flow potential , the intake can show no significant gains past that heads flow level, significantly reducing the hp/tq numbers the intake test will show yet the intake still may have far greater potential and the fact that the larger the displacement and higher the compression the more effective the high flow intakes become!

my PORTED STEALTH RAM produced far better power with both a
CRANE 119661
http://www.cranecams.com/product/cart.p ... il&p=24188


and CROWER 00471s

than with cams that worked correctly with the PORTED TPI with high flow runners, this cam below,worked great at the track, on a 406 sbc I helped build for a friend,with AFR 210cc heads,hooker headers and a 10.5:1 cpr with a manual transmission and 3.73 rear gears
crane 119681
http://www.cranecams.com/product/cart.p ... il&p=24190

but had less than ideal street manors,

you might find these threads below useful
most of the current low rise 4 barrel intakes designed for street use fall in the 240cfm-260cfm range in stock out of the box form, the better single plane, intakes tend to run 20cfm or so higher, either style can be ported to increase the flow rates.
CALCULATORS
http://www.wallaceracing.com/calcafhp.php

http://www.wallaceracing.com/calchpaf.php

http://www.rbracing-rsr.com/runnertorquecalc.html

http://horsepowercalculators.net/intake ... old-design



viewtopic.php?f=55&t=58

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viewtopic.php?f=52&t=5537&p=16750&hilit=1206+1207#p16750

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viewtopic.php?f=52&t=462&p=11902&hilit=1206+1207#p11902

viewtopic.php?f=55&t=1038

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viewtopic.php?f=55&t=5378
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: just how restrictive are the stock TPI engine components?

Postby Doodad » November 5th, 2010, 12:25 am

Great info Grump I just wanted to chirp in here, To get those pesky Stealth to fit under a low slung hood just cut em like this:http://www.digitalcorvettes.com/forums/showthread.php?t=59726 or this:http://forums.corvetteforum.com/c4-general-discussion/2073962-holley-stealth-ram-for-your-c4-l98-2.html ,cool article you have to be confident to cut in to your brand new $500 intake :lol: Or this guy here..http://forums.corvetteforum.com/c4-gene ... l...here's some flow #'s for the TPI and Aftermarket Intakes(i dont know if they are accurate)...http://forums.corvetteforum.com/c4-tech ... ow-s.html..
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Re: just how restrictive are the stock TPI engine components

Postby grumpyvette » November 5th, 2010, 6:33 am

none of the you links posted work for me,
and no, I designed and tested a completely new plenum rather than cut up the old O.E.M. plenum as there were several very obvious areas that could be improved, research showed it was a good basic design but it could be improved a great deal, provided you have a mill and a tig welder and a good basic understanding of air flow and where the O.E.M. intake was restricting flow,as you saw I've got all the tools required and have tested easily a dozen or more plenum designs, theres no way to get the max potential flow characteristics from a cut and patch based on the original plenum.
keep in mind HOLLEY can't take the time and effort required to maximize the intakes potential and still maintain an economically viable to market intake platform, that's one reason why they based the stealth ram on a previously designed carburetor equipped tunnel-ram, and made the required mods to get it to function as an EFI platform

read thru this thread also

viewtopic.php?f=55&t=1745&p=4378&hilit=+stealth#p4378


IF your thinking of installing a LT4 intake on the first generation small block chevy engine theres a few required mods that will be necessary.
I really hope you took the effort to read thru the links and sub links so you understand the changes required to get that lt4 style intake to fit and function,if your installing that intake on the first gen engine rather than the LT4 engine
obviously youll need the matched throttle body, injectors,gaskets, sensors and fuel rails and connections
obviously you'll need a crank triggered distributor-less ignition or modifications to use a distributor,THAT FITS AND CLEARS THE INTAKE and mods to route coolant flow to the water pump and block that the current LT4 intake was not designed for but can be modified for.
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http://sethirdgen.org/LT1.htm

viewtopic.php?f=70&t=5916&p=18181&hilit=+ignition+coil+plug#p18181

viewtopic.php?f=55&t=1052

http://www.popularhotrodding.com/tech/0 ... rsion_ls1/

http://www.eecis.udel.edu/~davis/z28/lt ... onversion/
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: just how restrictive are the stock TPI engine components?

Postby Doodad » November 13th, 2010, 12:24 am

Ill try to fix the links, I meant cutting the stealth or mini ram, another good tip is to grind the front EGR port in the front of the plenum (But not to far you'll go clean through ruining the plenum) also knock the castings from the inside of runner tubes on the top of runner (The bottom lip was designed to rotate the air charge before entering the intake) Siamese and gasket match runners to plenum and intake then you can work on the heads to handle your new airflow.I prefer the stock lookin runners or stock but thats just me.
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Re: just how restrictive are the stock TPI engine components

Postby grumpyvette » January 13th, 2015, 12:39 pm

if your considering use of the SBC HOLLEY single plane intake be aware it will require some careful hand porting to flow well, its a good design but the ports and runner entrances and plenum as it comes out of the box can use a good deal of custom porting to allow it to flow at near its potential, you can very easily boost flow 30 cfm per runner with a few hours with a die grinder, heres a few pictures of a HOLLEY EFI intake after the port and runner clean up work, the BBC versions still require some work to flow to their potential but are not as restrictive out of the box

SBC (4160 carb size TB base)
http://www.summitracing.com/parts/hly-9 ... /overview/

BBC (RECTANGLE)(4160 carb size TB base)
http://www.summitracing.com/parts/hly-9 ... /overview/

BBC (OVAL)(4160 carb size TB base)
http://www.summitracing.com/parts/hly-9 ... /overview/

BBC (RECTANGLE) DOMINATOR SIZE TB
http://www.summitracing.com/parts/hly-9 ... /overview/

viewtopic.php?f=52&t=462&hilit=porting+help

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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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