Carburated L98 - Dyno sheet?
Thread Starter
Racer
Joined: Oct 2007
Posts: 442
Likes: 15
From: FL
Carburated L98 - Dyno sheet?
Thinking about carbing a 1989 L98. Engine will be going into a 79 Impala.
I know I could make more power with the carb but this would be up high revs as the L98 TPI intake makes torq down low. Will I loose lb-ft down low, if so, how much?
Would luv to see a dyno sheet from an otherwise "stock" L98 with any intake (preferably EB Perf or Sum Stage 1) and Q-jet.
I know I could make more power with the carb but this would be up high revs as the L98 TPI intake makes torq down low. Will I loose lb-ft down low, if so, how much?
Would luv to see a dyno sheet from an otherwise "stock" L98 with any intake (preferably EB Perf or Sum Stage 1) and Q-jet.
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
Thinking about carbing a 1989 L98. Engine will be going into a 79 Impala.
I know I could make more power with the carb but this would be up high revs as the L98 TPI intake makes torq down low. Will I loose lb-ft down low, if so, how much?
Would luv to see a dyno sheet from an otherwise "stock" L98 with any intake (preferably EB Perf or Sum Stage 1) and Q-jet.
I know I could make more power with the carb but this would be up high revs as the L98 TPI intake makes torq down low. Will I loose lb-ft down low, if so, how much?
Would luv to see a dyno sheet from an otherwise "stock" L98 with any intake (preferably EB Perf or Sum Stage 1) and Q-jet.
Thread Starter
Racer
Joined: Oct 2007
Posts: 442
Likes: 15
From: FL
I know the swap to only carb without cam or other internals is probably not worth dyno´ing in some people´s eyes. :-)
Anyways, would be great if somebody would have a dyno sheet. I have searched the web but came up with nothing.
Anyways, would be great if somebody would have a dyno sheet. I have searched the web but came up with nothing.
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
There are many dyno tests on 350 smallblocks on the internet and many were done by Westech Performance. I recall a test on a 9.7 c r 350 comparing the L79 cam with the little comp 252 cam with 206 206 @ 050 430 lift 110 lsa. The 252 cam made 349hp at 5100 and 388 tq @ 3900 and the l79 cam 222 222 @050 114 LSA made 350 hp @ 5400 and 380 tq @ 4100 rpm. Many more tests on the internet so start searching! I ran the comp 252 in a stock 305 sbc in my wife's 87 formula firebird and was a great little cam.
Le Mans Master
Joined: Aug 2017
Posts: 6,943
Likes: 1,490
From: New Jersey
Not a stock comparison but Richard holdner did a comparison on a worked motor. But the curves will still follow the same pattern... it lost 40 numbers in torque from around 3000-4000 but bottom bottom was similar. It improved the top end where it flattens out normally at 4500 though. Should behave in a similar manner... dual plane with a carb is a solid all around intake imo.
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
No dyno tests, just my butt dyno. Your L98 is nothing special it's just a 350 so do some research on carbed 350 dyno tests and forget about finding carbed L98 dyno tests!
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Not a stock comparison but Richard holdner did a comparison on a worked motor. But the curves will still follow the same pattern... it lost 40 numbers in torque from around 3000-4000 but bottom bottom was similar. It improved the top end where it flattens out normally at 4500 though. Should behave in a similar manner... dual plane with a carb is a solid all around intake imo.
All you're doing with the different intake is getting rid of the mid range "bump" in torque that the TPI creates. Corvette Stories
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Thread Starter
Racer
Joined: Oct 2007
Posts: 442
Likes: 15
From: FL
Well, the improvement of the L98 over the SB seems to start at 2,000 rpm, as to the below chart.
I hoped the L98 with better flowing heads and 9.5:1 CR would do better - significantly better - than your regular 8,5:1 CR 190hp 350 with stock iron smog heads. Actually, even better than a cammed 350.
Here is the comparison of a stock L98 (TPI still) to a cammed 350 Targetmaster of a friend of mine:
I am mostly interested in the L98, because tq and hp are generated at lower rpms. I don´r race and I don´t cruise at 5,000 rpm. To move the Impala, torq at lower rpm is what I am looking for.
You may right, tho, that this "bump" will be lost with swapping the intake, as the long TPI runners are said to be the reason for improved figures.
I hoped the L98 with better flowing heads and 9.5:1 CR would do better - significantly better - than your regular 8,5:1 CR 190hp 350 with stock iron smog heads. Actually, even better than a cammed 350.
Here is the comparison of a stock L98 (TPI still) to a cammed 350 Targetmaster of a friend of mine:
I am mostly interested in the L98, because tq and hp are generated at lower rpms. I don´r race and I don´t cruise at 5,000 rpm. To move the Impala, torq at lower rpm is what I am looking for.
You may right, tho, that this "bump" will be lost with swapping the intake, as the long TPI runners are said to be the reason for improved figures.
Last edited by colonel328; Dec 23, 2020 at 03:29 PM.
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
Well, the improvement of the L98 over the SB seems to start at 2,000 rpm, as to the below chart.
I hoped the L98 with better flowing heads and 9.5:1 CR would do better - significantly better - than your regular 8,5:1 CR 190hp 350 with stock iron smog heads. Actually, even better than a cammed 350.
Here is the comparison of a stock L98 (TPI still) to a cammed 350 Targetmaster of a friend of mine:
I am mostly interested in the L98, because tq and hp are generated at lower rpms. I don´r race and I don´t cruise at 5,000 rpm. To move the Impala, torq at lower rpm is what I am looking for.
You may right, tho, that this "bump" will be lost with swapping the intake, as the long TPI runners are said to be the reason for improved figures.
I hoped the L98 with better flowing heads and 9.5:1 CR would do better - significantly better - than your regular 8,5:1 CR 190hp 350 with stock iron smog heads. Actually, even better than a cammed 350.
Here is the comparison of a stock L98 (TPI still) to a cammed 350 Targetmaster of a friend of mine:
I am mostly interested in the L98, because tq and hp are generated at lower rpms. I don´r race and I don´t cruise at 5,000 rpm. To move the Impala, torq at lower rpm is what I am looking for.
You may right, tho, that this "bump" will be lost with swapping the intake, as the long TPI runners are said to be the reason for improved figures.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
The TPI runner length is entirely responsible for the tq "bump" in the area around 3200 RPM.....and also entirely responsible for the nose dive above 4500.
Thread Starter
Racer
Joined: Oct 2007
Posts: 442
Likes: 15
From: FL
Krusty, I belive both engines have been worked on, but thank you for the sheet as a mere curve course comparison.
Wilcar, yes gears, but they will up the highways revs. I was thinking about a TH700 for better power in 1st and lower revs in 4th. The 700 is 3.06 in 1st, IIRC.
Wilcar, yes gears, but they will up the highways revs. I was thinking about a TH700 for better power in 1st and lower revs in 4th. The 700 is 3.06 in 1st, IIRC.
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
Krusty, I belive both engines have been worked on, but thank you for the sheet as a mere curve course comparison.
Wilcar, yes gears, but they will up the highways revs. I was thinking about a TH700 for better power in 1st and lower revs in 4th. The 700 is 3.06 in 1st, IIRC.
Wilcar, yes gears, but they will up the highways revs. I was thinking about a TH700 for better power in 1st and lower revs in 4th. The 700 is 3.06 in 1st, IIRC.