L98 Redline
Thread Starter
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
L98 Redline
My car has been on blocks for awhile and I've forgotten....What's the redline for L98's? especially 1989 or thereabouts.
A web search showed the LT1 as being 5700rpm -- 700 higher than the L98! The only other site I found showed a 1991 L98 redlining @ 5200rpms. (To be clear, I'm NOT talking about peak power rpms!)
D@MN!... I didn't remember it being THAT low! Maybe I'm not being so conservative in my goals to build a 5k-5.5k rpm setup -- reusing my 55k production short block.
Is the heavy pistons the problem?
gp
A web search showed the LT1 as being 5700rpm -- 700 higher than the L98! The only other site I found showed a 1991 L98 redlining @ 5200rpms. (To be clear, I'm NOT talking about peak power rpms!)
D@MN!... I didn't remember it being THAT low! Maybe I'm not being so conservative in my goals to build a 5k-5.5k rpm setup -- reusing my 55k production short block.
Is the heavy pistons the problem?
gp
Safety Car
Joined: Oct 2008
Posts: 4,022
Likes: 30
From: Los Angeles CA
My car has been on blocks for awhile and I've forgotten....What's the redline for L98's? especially 1989 or thereabouts.
A web search showed the LT1 as being 5700rpm -- 700 higher than the L98! The only other site I found showed a 1991 L98 redlining @ 5200rpms. (To be clear, I'm NOT talking about peak power rpms!)
D@MN!... I didn't remember it being THAT low! Maybe I'm not being so conservative in my goals to build a 5k-5.5k rpm setup -- reusing my 55k production short block.
Is the heavy pistons the problem?
gp
A web search showed the LT1 as being 5700rpm -- 700 higher than the L98! The only other site I found showed a 1991 L98 redlining @ 5200rpms. (To be clear, I'm NOT talking about peak power rpms!)
D@MN!... I didn't remember it being THAT low! Maybe I'm not being so conservative in my goals to build a 5k-5.5k rpm setup -- reusing my 55k production short block.
Is the heavy pistons the problem?
gp
Safety Car
Joined: Jul 2008
Posts: 3,966
Likes: 4
From: Made In America
St. Jude Donor '10-'11
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Racer
Joined: Nov 2005
Posts: 456
Likes: 3
From: Sumner Texas
5,200 would be a reasonable redline for a stock L98.
I hope that Aardwolf was running an improved flow intake system when he was spinning it to 6,000 RPM.
What is limiting this version of the 350 Chevy is the intake system. Anyone who has ever driven one knows that it seriously runs out of steam at about 4,500 RPM. This 5,000 RPM anemia is due to the TPI manifolds restrictions at that engine speed. This restriction causes SERIOUS tension on the rods at higher RPM because that engine is sucking for air like a Marathon runner wearing a gas mask. That increased load on the rods is SERIOUS and can easily lead to a broken rod.
Take that same long block and put a free breathing intake on top of it with no changes to the lower end and the Red Line could be safely increased significantly.
Doc
I hope that Aardwolf was running an improved flow intake system when he was spinning it to 6,000 RPM.
What is limiting this version of the 350 Chevy is the intake system. Anyone who has ever driven one knows that it seriously runs out of steam at about 4,500 RPM. This 5,000 RPM anemia is due to the TPI manifolds restrictions at that engine speed. This restriction causes SERIOUS tension on the rods at higher RPM because that engine is sucking for air like a Marathon runner wearing a gas mask. That increased load on the rods is SERIOUS and can easily lead to a broken rod.
Take that same long block and put a free breathing intake on top of it with no changes to the lower end and the Red Line could be safely increased significantly.
Doc
Thread Starter
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
Oh yeah... that's why I was thinking a TPI was a better choice...No need to run it to 6000rpms on a regular basis. Beach Bum said 6k rpms could be done all day long for years....
Sounds iffy to me.
gp
Safety Car
Joined: Oct 2008
Posts: 4,022
Likes: 30
From: Los Angeles CA
ya right, although the mid and top end punch on my super ram is unbelievable,with my cam, it's been a bear to tune the idle off idle transition, but we are coming along, it smoothed way out, and the singlemass flywheel ding at the bottom end is starting to appear less appearent.
Thread Starter
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
Burning Brakes
Joined: Jan 2003
Posts: 755
Likes: 32
From: Roswell Georgia
If you're using a stock cam, 4700 RPM is as high as you need go before shifting to the next higher gear ratio to keep your vehicle in it's best torque band.
Don't count on an ECM fuel cutoff to protect you from exceeding the self-destruct limit of the rotating assembly. From what I remember, the fuel cutoff for L98's is roughly 8000
RPM.
Don't count on an ECM fuel cutoff to protect you from exceeding the self-destruct limit of the rotating assembly. From what I remember, the fuel cutoff for L98's is roughly 8000
RPM.
Safety Car
Joined: Oct 2008
Posts: 4,022
Likes: 30
From: Los Angeles CA
The engine powers through the 5.5k no problem but my 3.33 gears, breaks all speed limits in second.
so I say depends on you tranny and rear end and intended usage, street? stay with siamesed SLP runners and port everything.
Racer
Joined: Nov 2005
Posts: 456
Likes: 3
From: Sumner Texas
That is CORRECT! It just can't do it all the time, reliably with an L98 intake system on it due to the high RPM rod tension while trying to draw air through a straw.
I expect that the later LT engine has the same crank/rods. Again, the limitation is the restrictive intake system. It not only serves to limit the effective high RPM power, but also causes added stress for those who go beyond the redline.
I expect that the later LT engine has the same crank/rods. Again, the limitation is the restrictive intake system. It not only serves to limit the effective high RPM power, but also causes added stress for those who go beyond the redline.
