L98 Engine Mods - What works?
Racer
Joined: Nov 2005
Posts: 456
Likes: 3
From: Sumner Texas
Your combination is good, the only thing I would change is the cam to a slightly smaller HR like the hot cam or TPIS ZZ-9 cam. With the TPI you will be out ouf breath by 5000 RPM so you need to keep the intake duration under 220 degrees for best results. I had a very similar combination and it made approximately 350 HP and ran mid to high 12's in the quarter.
The recipe is coming along well. Just make SURE that you keep the low and midrange in mind for all components. It's all in the combination.
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Cool.... revised plan:
*Stock rods and crank
*New pistons - 10:1 compression
*Trickflow 195cc L98 heads
*TPIS BigMouth intake runners and base
*Custom ground cam to suit engine specs - 218/218 .500" 112 LSA - something like that
*1 5/8" headers with twin 2.5" pipes
*Custom dyno tune
Along with a 3.07 or 3.54 (is there something in between for the Dana 36??) diff ratio - should be lots of fun to drive...
*Stock rods and crank
*New pistons - 10:1 compression
*Trickflow 195cc L98 heads
*TPIS BigMouth intake runners and base
*Custom ground cam to suit engine specs - 218/218 .500" 112 LSA - something like that
*1 5/8" headers with twin 2.5" pipes
*Custom dyno tune
Along with a 3.07 or 3.54 (is there something in between for the Dana 36??) diff ratio - should be lots of fun to drive...
maybe send it off to corvetteplenum.com or do it yourself.
Burning Brakes
Joined: Aug 2000
Posts: 1,146
Likes: 2
From: Albuquerque NM
300 hp is possible with stock TPI...not much more TPI max flow is 220ish
350 hp is possible with 100% aftermarket TPI components and all tricks..240-260 ish for flow
400-500 is possible with Superram (more ramming effect at 4500 rpm)...250-280idh for floe
350-550ish is possible with miniram (more CFM)...300-340 cfm for flow
Most of the holley/edelbrock will be in the 300-340 range but cheaper than TPiS
obviously, no reason to get heads (AL L98 heads will flow 210ish) until intake is done
The better heads/intake/exhaust you have the less cam you need, just aim for .550-.575 lift for hyd roller. Nothing wrong with the ligenfelter spec of 219/219. But some go with a comp cams 224/230.
Le Mans Master
Joined: May 2007
Posts: 8,448
Likes: 27
From: Valparaiso
6
300 hp is possible with stock TPI...not much more TPI max flow is 220ish
350 hp is possible with 100% aftermarket TPI components and all tricks..240-260 ish for flow
400-500 is possible with Superram (more ramming effect at 4500 rpm)...250-280idh for floe
350-550ish is possible with miniram (more CFM)...300-340 cfm for flow
Most of the holley/edelbrock will be in the 300-340 range but cheaper than TPiS
obviously, no reason to get heads (AL L98 heads will flow 210ish) until intake is done
The better heads/intake/exhaust you have the less cam you need, just aim for .550-.575 lift for hyd roller. Nothing wrong with the ligenfelter spec of 219/219. But some go with a comp cams 224/230.
300 hp is possible with stock TPI...not much more TPI max flow is 220ish
350 hp is possible with 100% aftermarket TPI components and all tricks..240-260 ish for flow
400-500 is possible with Superram (more ramming effect at 4500 rpm)...250-280idh for floe
350-550ish is possible with miniram (more CFM)...300-340 cfm for flow
Most of the holley/edelbrock will be in the 300-340 range but cheaper than TPiS
obviously, no reason to get heads (AL L98 heads will flow 210ish) until intake is done
The better heads/intake/exhaust you have the less cam you need, just aim for .550-.575 lift for hyd roller. Nothing wrong with the ligenfelter spec of 219/219. But some go with a comp cams 224/230.
I will be getting a set of AFR 180 heads the flow 260cfm aprox
so i know this will be overkill for my stock TPI intake.-
anyway i have zz4 cam and 1.5 full rollers plus longtube headers.-
Next year my goal is to swap intake but i don't want to lose the nice low rpm torque so i've been researching and i guess one of the good systems out there is the FIRST TPI SYSTEM or maybe i will get the HI-FLO Edelbrock base and runners,i can't remember where i see a flow chart of different TPI combos,any info about this flow charts ?
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Calderone: I already posted a link to the Comp Cams TPI Shootout in post #45 -- earlier in this thread.
The best TPI flow comparisons can be found here. Unless these measurements are incorrect, you'll see that some of ZD1's figures would require porting to achieve.
The best TPI flow comparisons can be found here. Unless these measurements are incorrect, you'll see that some of ZD1's figures would require porting to achieve.
Le Mans Master
Joined: May 2007
Posts: 8,448
Likes: 27
From: Valparaiso
Calderone: I already posted a link to the Comp Cams TPI Shootout in post #45 -- earlier in this thread.
The best TPI flow comparisons can be found here. Unless these measurements are incorrect, you'll see that some of ZD1's figures would require porting to achieve.
The best TPI flow comparisons can be found here. Unless these measurements are incorrect, you'll see that some of ZD1's figures would require porting to achieve.
Thanks for the link Gregg ! sorry for the 2ble link.-
Le Mans Master
Joined: May 2007
Posts: 8,448
Likes: 27
From: Valparaiso
Edelbrock HIFLO is really decent !
Edelbrock Performer RPM manifold (Stock)................................. ....286.51 cfm
is this the HI FLO ??? I Remember a thread where they say Edelbrock,Accel and Lingenfelter bases are the same thing...
which is the best base / runner combo ?
Edelbrock Performer RPM manifold (Stock)................................. ....286.51 cfm
is this the HI FLO ??? I Remember a thread where they say Edelbrock,Accel and Lingenfelter bases are the same thing...
which is the best base / runner combo ?
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
The Eledbrock RPM manifold is for carburetors.
Id use the FIRST over any of the other TPI type intakes, dont feel the Edelbrock pieces will come close, they will still choke the heads. Defintely better than stock though.
Id use the FIRST over any of the other TPI type intakes, dont feel the Edelbrock pieces will come close, they will still choke the heads. Defintely better than stock though.
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Le Mans Master
Joined: May 2007
Posts: 8,448
Likes: 27
From: Valparaiso
i've been trying to look on FIRST flow chart numbers here with no luck
they only have some torque numbers on their site
any info ? Thanks , btw how many FIRST tpi vettes do we have here ???
Drifting
Joined: Feb 2008
Posts: 1,267
Likes: 27
From: Texas
Quinny,
Also.... I am relatively familiar with the differences in the Ford V8's from down under and how the components differ from those we have here. There are some really great combinations that can be built with certain combinations of US pieces and Australian pieces.
When it comes to the Chevies down under, my guess is that there are little or no differences. Chevy has always been better at interchangability than brand F.
If I am correct, then there are probably many great parts available in your salvage yards.
If you wanted to build the ultimate L98 Torque Beast, if you could use a small block Chevy 400 crankshaft with the mains turned down to 350 size and some dished, hypereutectic pistons, you could build a stroked 350 commonly called a 383 here.
If parts availability is similar to here, (the US) then the 383 crankshaft and pistons should be available. The 383 adds torque in two ways; it adds displacement AND it adds torque due to the longer crankshaft arm providing mechanical advantage.
A 383 would add enough torque that you might be able to get by with the 270 cam you mentioned without giving up bottom end. In this case, you would have to open up the runners and base or go to aftermarket, but you could make a car that would probably break the tires loose by just blipping the throttle.
In the small block Chevy world the 383 is the torque king.
Something to think about.
Also.... I am relatively familiar with the differences in the Ford V8's from down under and how the components differ from those we have here. There are some really great combinations that can be built with certain combinations of US pieces and Australian pieces.
When it comes to the Chevies down under, my guess is that there are little or no differences. Chevy has always been better at interchangability than brand F.
If I am correct, then there are probably many great parts available in your salvage yards.
If you wanted to build the ultimate L98 Torque Beast, if you could use a small block Chevy 400 crankshaft with the mains turned down to 350 size and some dished, hypereutectic pistons, you could build a stroked 350 commonly called a 383 here.
If parts availability is similar to here, (the US) then the 383 crankshaft and pistons should be available. The 383 adds torque in two ways; it adds displacement AND it adds torque due to the longer crankshaft arm providing mechanical advantage.
A 383 would add enough torque that you might be able to get by with the 270 cam you mentioned without giving up bottom end. In this case, you would have to open up the runners and base or go to aftermarket, but you could make a car that would probably break the tires loose by just blipping the throttle.
In the small block Chevy world the 383 is the torque king.
Something to think about.
but a problem I see with the bigger cubes is more to feed so instead of 4500rpm being the wall it feels like 4000-4200
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Why in the world are you thinking of changing pistons if you only want 350hp? Save your cash and get a better intake manifold if you want some real difference. 
There's too many opinions and cooks in this kitchen. You really need to stop back and first make a budget then dedice what *you* want to do with the car. Are you trying to hit a certain power # for some reason, hit a particular ET, improve x.xx on a road course or Auto-X, or just smile factor?
The L98 is essentially the same ole' SBC they've been using since the 50s and responds very well to modification if you ensure you're not just slapping random parts on. If you want a laugh, go unbolt your stock manifolds. Once you'll see the inside of them then you'll realize your car has two major problems. First it is aesthmatic trying to suck air through the TPI and second it is trying to **** through it's own fist with the rediculously tiny manifolds.
If you can go for an 87 or higher as there were a number of improvements like the roller lifter cam and the 128 aluminum heads for certain (only some 86 have them). If you find a new '88 then you get the D-Port 113 aluminum heads which flow even better than the 128 castings.
There's too many opinions and cooks in this kitchen. You really need to stop back and first make a budget then dedice what *you* want to do with the car. Are you trying to hit a certain power # for some reason, hit a particular ET, improve x.xx on a road course or Auto-X, or just smile factor?
The L98 is essentially the same ole' SBC they've been using since the 50s and responds very well to modification if you ensure you're not just slapping random parts on. If you want a laugh, go unbolt your stock manifolds. Once you'll see the inside of them then you'll realize your car has two major problems. First it is aesthmatic trying to suck air through the TPI and second it is trying to **** through it's own fist with the rediculously tiny manifolds.
If you can go for an 87 or higher as there were a number of improvements like the roller lifter cam and the 128 aluminum heads for certain (only some 86 have them). If you find a new '88 then you get the D-Port 113 aluminum heads which flow even better than the 128 castings.
Advanced
Joined: Nov 2008
Posts: 85
Likes: 1
I see,i thought there was a Edelbrock TPI Base like the Performer heads they have for 87-91 L98's.-
i've been trying to look on FIRST flow chart numbers here with no luck
they only have some torque numbers on their site
any info ? Thanks , btw how many FIRST tpi vettes do we have here ???
i've been trying to look on FIRST flow chart numbers here with no luck
they only have some torque numbers on their site
any info ? Thanks , btw how many FIRST tpi vettes do we have here ???
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
FYI: Skip forward about 6 minutes if you want to see where the real racing starts. The total video is about 18 minutes long.
I particularly enjoyed this video since my upcoming build should produce similar results/characteristics. And, I thought others might be interested in how a strong TPI upgrade can perform.
Note: For added clarity, his short-block is a GM performance 350 --basically a stock L98 replacement short-block. He's running a stock tune (on his 89 MAF car).
Burning Brakes
Joined: Aug 2005
Posts: 1,172
Likes: 9
From: '88 TPI L98/HotCam Powell, Ohio
Here's the link Gregg was talking about (Mid Ohio big Bore Race Group). I qualified up front in the middle of Super Unlimited and ST1/2 cars. Click ahead to ~5 minutes for the start....
http://vimeo.com/5585635
Matt
http://vimeo.com/5585635
Matt
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Here's the link Gregg was talking about (Mid Ohio big Bore Race Group). I qualified up front in the middle of Super Unlimited and ST1/2 cars. Click ahead to ~5 minutes for the start....
http://vimeo.com/5585635
http://vimeo.com/5585635
Thanks Matt. Forgetting to post the link was all part of my plan for you to post it yourself and get the lime-light!
Safety Car
Joined: Feb 1999
Posts: 4,724
Likes: 16
From: Little Elm TX
Here's the link Gregg was talking about (Mid Ohio big Bore Race Group). I qualified up front in the middle of Super Unlimited and ST1/2 cars. Click ahead to ~5 minutes for the start....
http://vimeo.com/5585635
Matt
http://vimeo.com/5585635
Matt
Was fun to watch..... I'm a wannabe roadracer, so do not know a lot about it, but it looked to me like you could run with anybody thru the twisty stuff..... in the straightaway is where some of those guys pulled away. I'm thinking a few more modifications and nobody will be going around you.
Do you have a HP limit or modification limit in your class ?
btw, what are your modifications right now ?
