Do you prefer Top Mounted or Bottom Mounted?
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 847
Likes: 729
From: Houston, TX
Do you prefer Top Mounted or Bottom Mounted?
The majority of Twin Turbo C8s I've seen are bottom mounted, with many of those originating as kit systems from ETS (Extreme Turbo Systems). Cicio and Jotech seem to have many bottom mount installations under their belts. LMR (Latemodel Racecraft) seems to have focused on the top mounted approach and have been very successful with their drag strip results.
What do you all see as the Pros/Cons of Top VS Bottom mounted Twin Turbos on the C8? Installation? Cooling? Appearance? Efficiency? Reliability? Performance? Other?
Also, please feel free to add any other insight/perspective you might have on Twin Turbos in general.
What do you all see as the Pros/Cons of Top VS Bottom mounted Twin Turbos on the C8? Installation? Cooling? Appearance? Efficiency? Reliability? Performance? Other?
Also, please feel free to add any other insight/perspective you might have on Twin Turbos in general.
Drifting
Joined: Aug 2019
Posts: 1,859
Likes: 1,264
From: Houston
Bottom mount seems like it’d be easier overall to install. Should be cooler too since the turbos aren’t in the engine bay and provide better weight balance. Not sure if it’s due to a lack of space but you’ll notice most TT lambos/r8s have it bottom mounted.
Supporting Vendor
Joined: Mar 2020
Posts: 733
Likes: 546
From: Atlanta, GA
The majority of Twin Turbo C8s I've seen are bottom mounted, with many of those originating as kit systems from ETS (Extreme Turbo Systems). Cicio and Jotech seem to have many bottom mount installations under their belts. LMR (Latemodel Racecraft) seems to have focused on the top mounted approach and have been very successful with their drag strip results.
What do you all see as the Pros/Cons of Top VS Bottom mounted Twin Turbos on the C8? Installation? Cooling? Appearance? Efficiency? Reliability? Performance? Other?
Also, please feel free to add any other insight/perspective you might have on Twin Turbos in general.
What do you all see as the Pros/Cons of Top VS Bottom mounted Twin Turbos on the C8? Installation? Cooling? Appearance? Efficiency? Reliability? Performance? Other?
Also, please feel free to add any other insight/perspective you might have on Twin Turbos in general.
The main advantage of the bottom mount is that it works with both Coupes and HTC Models whereas the top mount system does not.
The bottom mount will keep more heat out of the engine bay as well.
An advantage of the top mount kit is that you can reuse the factory cats and exhaust but in our experience anyone looking to turbo their C8 will want to swap these OEM exhaust components out anyways.
Thanks
Andrew
Supporting Vendor
Joined: Feb 2009
Posts: 4,421
Likes: 1,430
From: Mesa Az
I'd go bottom mount every time, just from a heat standpoint and ease of working on the car.
__________________
Cordes Performance Racing aka "CPR"
Owner of AZ's premier LSX/LTX motorsports shop
http://cordesperformanceracing.com/
www.facebook.com/cordesperformanceracing.com
joe@cordesperformanceracing.com
480-359-5914
Cordes Performance Racing aka "CPR"
Owner of AZ's premier LSX/LTX motorsports shop
http://cordesperformanceracing.com/
www.facebook.com/cordesperformanceracing.com
joe@cordesperformanceracing.com
480-359-5914
5th Gear
Joined: Dec 2022
Posts: 5
Likes: 6
Top mounts are going to spool faster than rear(bottom mounts) but most of these systems are used on the street where most won't notice a difference. If I were building one, I would start with a custom header 1 3/4 stepped down to a 1 5/8" into a merge collector with a 2" down to the turbo. Wrap or coat everything for thermal retention and blanket the turbo.
Phil
Phil
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 847
Likes: 729
From: Houston, TX
Top mounts are going to spool faster than rear(bottom mounts) but most of these systems are used on the street where most won't notice a difference. If I were building one, I would start with a custom header 1 3/4 stepped down to a 1 5/8" into a merge collector with a 2" down to the turbo. Wrap or coat everything for thermal retention and blanket the turbo.
Phil
Phil
Is the recommended step down in the header size to increase exhaust flow to the turbo? Faster spool up?
5th Gear
Joined: Dec 2022
Posts: 5
Likes: 6
Fwiw my last setup had 1 3/4" headers and a 2.5" combination and made north of 2500(450 ci canted valve LS). So anyone who tells you it won't work is wrong. It's all about velocity. I did enough testing to completely drain the wallet. 1 3/4 1 7/8 2" headers, 2.5/2.75/3" connections. Gas and alcohol.
Thread Starter
Burning Brakes
Joined: Aug 2004
Posts: 847
Likes: 729
From: Houston, TX
Yes, turbos rely on drive pressure to generate boost. Correctly sizes headers and connection piping will allow faster spool with a larger turbine resulting in lower backpressure at high boost levels.
Fwiw my last setup had 1 3/4" headers and a 2.5" combination and made north of 2500(450 ci canted valve LS). So anyone who tells you it won't work is wrong. It's all about velocity. I did enough testing to completely drain the wallet. 1 3/4 1 7/8 2" headers, 2.5/2.75/3" connections. Gas and alcohol.
Fwiw my last setup had 1 3/4" headers and a 2.5" combination and made north of 2500(450 ci canted valve LS). So anyone who tells you it won't work is wrong. It's all about velocity. I did enough testing to completely drain the wallet. 1 3/4 1 7/8 2" headers, 2.5/2.75/3" connections. Gas and alcohol.
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
5th Gear
Joined: Dec 2022
Posts: 5
Likes: 6
Thanks for the additional explanation. Makes sense. On the flip side, could reducing the exhaust/header diameter have any detrimental impact on the factory calibrated performance? For example, if you weren't driving turbos and only reduced the exhaust size, you normally would expect a decrease in performance, right? But, I'm guessing that the increased boost would outweigh the "normal" performance reduction you might expect. ?
Your probably thinking there is no way tubes this small can be efficient. Think about your exhaust valve cross section at the valve seat and the turbine at the nozzle entry point.
Last edited by 95mmrenegade; Jan 3, 2023 at 07:27 AM.
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
trade offs. Top mounts allow the turbos to snug up to the exh port tighter for spooling, and can gravity drain the oil going back to the pan
rear mounts as mentioned will keep things cool and be easier to boost the vert
either way, the c8 will go like stink with the turbos spooled. The c8 with the dct won't suffer too much off boost in the lower rpms as the deep lower gears will get the rpms up quickly to spool.
rear mounts as mentioned will keep things cool and be easier to boost the vert
either way, the c8 will go like stink with the turbos spooled. The c8 with the dct won't suffer too much off boost in the lower rpms as the deep lower gears will get the rpms up quickly to spool.
