Incremental L98 intake airflow improvements

[86-ZZ3]

I'd like the esteemed members' opinions on this one.

I have a L98 that should be able to breathe (from plenum to exhaust - cammed, headered exhaust) and generate more hp than a stock L98.

The question I have is what incremental airflow inprovement I can make from air intake to throttle body?

Air flow intake: stock
Filter: K&N (been in place for 20+ years)
MAF: stock
MAF-throttle body: stock
Throttle body: stock other than the intake airfoil

Which of the above would be the most airflow restricted and hence would get the best bang for the buck?

 

[Schrade]

I'd like the esteemed members' opinions on this one.

I have a L98 that should be able to breathe (from plenum to exhaust - cammed, headered exhaust) and generate more hp than a stock L98.

The question I have is what incremental airflow inprovement I can make from air intake to throttle body?

Air flow intake: stock
Filter: K&N (been in place for 20+ years)
MAF: stock
MAF-throttle body: stock
Throttle body: stock other than the intake airfoil

Which of the above would be the most airflow restricted and hence would get the best bang for the buck?

Don't know if I'm 'esteemed' or not (I get 'steemed when I hear mechanics shafting people who can't tell the difference), but I can tell you that the flow design of the L98 intake is based on TPI 305, NOT the TPI 350.

 

[TedC]

Comments based on my trial and error on a stock 1988 and 1989.
Air flow intake: stock - Somewhat restrictive - open air intake adds a few upper RPM power (I can tell in WOT 1-2 shifts, especially in my 1989 with 3.07 rear end)
Filter: K&N (been in place for 20+ years) - Found no change over stock AC - Just don't over oil it. My 1988 came with one and the IAC was all gummed up. My local vette shop says no to oil based filters unless you really need the extra air flow.
MAF: stock - Have not found this restrictive. Designed to flow enough air for 5000 RPM. I tried pulling out rear screen then rear and front screen with no seat of the pants difference. Get some good MAF cleaner to clean the screens and wires.
MAF-throttle body: stock - ??? is the air tube?
Throttle body: stock other than the intake airfoil - tried a larger one, no seat of the pants improvement. Just make sure you remove it and clean behind the plates and IAC area. Air foil does help flow air better (adds 39 cfm) but is is really of minimal value on a stock L98. I feel you may see at best 5-8 HP gains playing with all the above. Real HP (say 20HP) is gained by changing the intake runners and intake manifold (as per comment from prior post on 305). I drove a L98 that had bigger runners and aftermarket intake manifold and the difference above 4000 RPM was significant.

 

[vetteboy86]

Suggested Mods for TPI engines - ThirdGen.org

This is a good read.

http://www.corvetteactioncenter.com...elp-increase-horsepower-l98-$2000-budget.html

All kinds of other good stuff here!

 

[86-ZZ3]

Thanks for the comments. I do have Edelbrock runners and baseplate. Not sure how many more cfm this flows.

II ask about the tube between the MAF and TB as the corrugation does cause airflow restriction but was wondering if springing $40 for a smooth tube is cost effective, or doesn't make any difference.

 

[vetteboy86]

If I recall correctly the smooth tube was prone to cracking. I dont see how it would hurt. If you feel that the gain is worth the money go for it. I'm still running the original, but understand how fulfilling it can be doing add ons to your vette.

 

[pologreen1]

my stock accordian tube is perfect, but I bought a smooth tube a few years ago, I like it, but it is heavy, because it has 3 metal rings inside to help it stay true to form.

 

[86-ZZ3]

The smooth tube in theory would make that bore much larger, but there's the the MAF and throttle body as restrictors.

Then again, the accordion tube connector would probably make the effective diameter at least 1" smaller.

http://www.mmmfg.com/pdfs/060612_AU_CC_HotandHumid.pdf

Bear in mind that a 350 c.i. engine at 2,000 rpm with a volumetric(?) efficiency of 90% would be taking in 180 cfm of air vs the study above.