L98 TPI Siamesed Intake Manifold Base
Thread Starter
Pro
Joined: Feb 2004
Posts: 641
Likes: 16
From: O'Fallon MO
L98 TPI Siamesed Intake Manifold Base
Joined: Jun 18, 2004
Posts: 1
Posted: Tue Jul 06, 2004 10:42 pm Post subject: L98 Siamesed intake manifold
--------------------------------------------------------------------------------
Has anyone experience with siamesing the adjacent ports in the stock L98 intake base? Looks like each cylinder will get to pull from two runners at a time instead of just one. Thats a lot more air than just one "large runner"at a time if you went with large runners and differnt base manifold. If you ground the walls out in the manifold yet kept the resulting runner inside the manifold to the valve at least 3 - 4 inches, will this be satisfactory?
:flag
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: L98 TPI Siamesed Intake Manifold Base (hardlight)
A copla years ago I did the siamese intake base mod to my L98. I initially cut a hole 1"x1", with a little rounding into the lower runner flange for streamlining. Dyno pulls before & after are on my site; they show that it gained 20chp at 5,400rpm with my air flow mods to date. She now pulls strongly through my 2-3 shift point of 5,700rpm.
I have subsequently opened the cut depth to 2" deep but don't yet have dyno results to know if there was any gain over the prior 1" depth.
You can check out the F-body forum http://www.thridgen.org/ for more info on this mod.
I would recommend this mod if you have done exhaust and some other air flow mods to your L98 and need an intake system mod so it will pull to higher RPM, at a "good price".
I have subsequently opened the cut depth to 2" deep but don't yet have dyno results to know if there was any gain over the prior 1" depth.
You can check out the F-body forum http://www.thridgen.org/ for more info on this mod.
I would recommend this mod if you have done exhaust and some other air flow mods to your L98 and need an intake system mod so it will pull to higher RPM, at a "good price".
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: L98 TPI Siamesed Intake Manifold Base (hardlight)
[SNIP]If you ground the walls out in the manifold yet kept the resulting runner inside the manifold to the valve at least 3 - 4 inches, will this be satisfactory? [/SNIP]
That's exactly what I did. I removed the wall between the runner pairs in the intake manifold as far in as I could reach with my SawAll blade.
When I finished, I measured 3-1/2 to 4" of divider wall remaining. I wrote down the exact figure of remaining wall, but I can't lay my hands on the paper right now.
I also used a cartridge roll chucked in my electric drill to round out the openings at the runner end of the manifold (not the head end). I used coarse, medium and then fine grits. The roll would only reach in part way because when the port begins to turn, the roll would bind, not being able to negotiate the turn. I did as best I could.
DEFINITE IMPROVEMENT. MaddMaxx put me on to doing this. I like yo give him credit for kicking my brain out of park.
Jake
That's exactly what I did. I removed the wall between the runner pairs in the intake manifold as far in as I could reach with my SawAll blade.
When I finished, I measured 3-1/2 to 4" of divider wall remaining. I wrote down the exact figure of remaining wall, but I can't lay my hands on the paper right now.
I also used a cartridge roll chucked in my electric drill to round out the openings at the runner end of the manifold (not the head end). I used coarse, medium and then fine grits. The roll would only reach in part way because when the port begins to turn, the roll would bind, not being able to negotiate the turn. I did as best I could.
DEFINITE IMPROVEMENT. MaddMaxx put me on to doing this. I like yo give him credit for kicking my brain out of park.
Jake
Thread Starter
Pro
Joined: Feb 2004
Posts: 641
Likes: 16
From: O'Fallon MO
L98 TPI Siamesed Intake Manifold Base
thanks for the responses, I'm getting my hands on a spare intake manifold and I thought I'd try and make the modifications and have it ready for a transplant when we put in a Hot Cam kit and headers. I thought this might be a way to keep from breaking the bank and get a lot of benefit from the cam and headers and my own sweat equity on the manifold.
Burning Brakes
Joined: Jun 2003
Posts: 1,229
Likes: 1
I just looked at the price of a super ram base manifold... holy! 459$ US. I'm in Canada that would be 690$ Canadian, plus shipping would be well over 700$ for me. Now I understand why people port the stock tpi instead of buying an aftermarket intake.
I would be very interested in porting my intake like the rest of you guys, but I'm a bit afraid of taking every thing apart and starting to grind in it without knowing were to start. I guess pictures would solve this problem and a bit more courage. I know I can always try to find some other TPI intakes on Ebay or something to grind.
I have a 383, with stock TPI intake, stock cam, stock injectors, stock chip and I'd like to install some LT headers one day. Should I really consider porting my intake? if yes, should I install an adjustable gas pressure regulator and consider reprogramming my computer chip or even going with bigger injectors?
I think the only reason why I'm getting away with no Fuel pressure regulator and the stock injectors on my 383 is because I have the stock cam and stock TPI intake, but if I port the TPI and install LT headers... what then?
I would be very interested in porting my intake like the rest of you guys, but I'm a bit afraid of taking every thing apart and starting to grind in it without knowing were to start. I guess pictures would solve this problem and a bit more courage. I know I can always try to find some other TPI intakes on Ebay or something to grind.
I have a 383, with stock TPI intake, stock cam, stock injectors, stock chip and I'd like to install some LT headers one day. Should I really consider porting my intake? if yes, should I install an adjustable gas pressure regulator and consider reprogramming my computer chip or even going with bigger injectors?
I think the only reason why I'm getting away with no Fuel pressure regulator and the stock injectors on my 383 is because I have the stock cam and stock TPI intake, but if I port the TPI and install LT headers... what then?
Last edited by TheStef; Jul 8, 2004 at 04:16 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
