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Trying to make the L98 breathe a little better (w/pics)

R

rel3rd

Guest
I am in on the AS&M Big Tube TPI Runner Group Purchase that was organized on a Camaro/Firebird site (thirdgen.org). I own an 85 Corvette and wanted to open up it's lungs a little bit to hopefully gain some upper rpm power. I've read all the Mini Ram, Stealth Ram, LT1 conversion threads I could read and decided I wanted the easiest (IMHO) swap for my car. Anyway, to go along with the AS&M runners, I also bought a new Edelbrock base intake and an extra plenum as well. I'm sure some will say it is a waste and to bolt on a blah-blah-blah intake instead, but I'm confident that I'll be happy with my end result.

The base is overall a very nice piece, but I wanted to "clean up" the casting internally, as well as slightly straighten the already much straighter than stock intake ports. Here's what I have done so far:
(just click on the links...I didn't want to dog down anyone with a ton of posted pics)

http://home.comcast.net/~rel3rd/wsb/media/373752/site1364.jpg
http://home.comcast.net/~rel3rd/wsb/media/373752/site1368.jpg

I can't "finish" the runner inlets until I get the actual new runners. That way I'll have the exact measurements and can open the intakes inlets to match. I did notice that the intake has a "dual pattern" on the 4 center bolt holes...Are these so the intake can be used on "regular" heads, as well as on Vortec style heads???

http://home.comcast.net/~rel3rd/wsb/media/373752/site1362.jpg
http://home.comcast.net/~rel3rd/wsb/media/373752/site1363.jpg

As for the plenum. I bought it used as a corvetteplenum.com ported unit, but did a good bit of clean-up on this myself. Basically, all I started with was a stock intake that had been cleaned up, had the TB openings hogged out a little, and had the runner sides siamesed. Not bad for the money, but I knew I could improve on what was already there. I opened up the area directly behind where the sides of TB openings will be, as well as did a good bit of smoothing to the plenum "roof" and "floor". The plenum's outlets were already siamesed, so I need to figure what I am going to do with the AS&M runner's entrances when I get them. I also intend to "port-match" the plenum's exits, with the runner's entrances. Here's some pics:

http://home.comcast.net/~rel3rd/wsb/media/373752/site1365.jpg
http://home.comcast.net/~rel3rd/wsb/media/373752/site1366.jpg
http://home.comcast.net/~rel3rd/wsb/media/373752/site1367.jpg

Assuming the intake swap goes as smoothly as it should...next cash outlay is a set of longtube headers and a matching Y pipe, then maybe some dyno-tuning to extract what I can from this old thing....Over the Winter a possible 1.6 roller rocker arm swap, and I've also been kicking around the idea of a little giggle gas...aka nitrous. :eek:
 

CTYANK2

Well-known member
Joined
Jan 6, 2003
Messages
172
Location
CONNECTICUT
Corvette
1989 Triple Black Convertible 2011 V-Yellow Z06
I have been thinking about similar mods on my 89 (auto w/3:07 gears and TPIS headers) but I was wondering if increasing the air flow in the plenum/runners/mainfold and keeping stock heads/cam is really worth the trouble? I'm not looking to improve 1/4 mile times, just street performance (0 to 60+mph). I guess you have stock cam/heads. What gains do you expect from opening up the intake as you described?
 

AdvancedAutoCC

Well-known member
Joined
Jan 8, 2004
Messages
381
Location
Cape Coral, FL
Corvette
'96 coupe (Torch Red), '85 4+3 coupe (flat black)
Over the Winter a possible 1.6 roller rocker arm swap, and I've also been kicking around the idea of a little giggle gas...aka nitrous. :eek:
I can hook you up with both of these items... just let me know!
 
R

rel3rd

Guest
I have been thinking about similar mods on my 89 (auto w/3:07 gears and TPIS headers) but I was wondering if increasing the air flow in the plenum/runners/mainfold and keeping stock heads/cam is really worth the trouble? I'm not looking to improve 1/4 mile times, just street performance (0 to 60+mph). I guess you have stock cam/heads. What gains do you expect from opening up the intake as you described?

I'm just going by everything I have heard/read about the TPI "stock" intake setup...the general consensus is that it is made for lower rpm torque, not upper rpm horsepower. I know mine hits a wall at 4600 rpm of so, as do many others. I really could care less about dragstrip performance either...already been there and done that...many times, lol. I'm wanting all around power additions. In other words, mods that don't make somewhere else in the power range suffer. I don't want/need a car that revs to 6500rpm's, but I would like to see power until at least 5200 rpm's or so. My car feels like it screams up until that 4600 rpm point, then falls over, gasping for air...I "may" add some nice heads and a better cam, but I think with just the induction opened up, and some better breathing exhaust, I'll be close to where I want to be without any heads or cam swaps.
 

Mad-Mic

Gone but not forgotten
Joined
Feb 12, 2002
Messages
1,853
Location
Annapolis Maryland
Corvette
1987 Redskin Red Coupe
I'm just going by everything I have heard/read about the TPI "stock" intake setup...the general consensus is that it is made for lower rpm torque, not upper rpm horsepower. I know mine hits a wall at 4600 rpm of so, as do many others. I really could care less about dragstrip performance either...already been there and done that...many times, lol. I'm wanting all around power additions. In other words, mods that don't make somewhere else in the power range suffer. I don't want/need a car that revs to 6500rpm's, but I would like to see power until at least 5200 rpm's or so. My car feels like it screams up until that 4600 rpm point, then falls over, gasping for air...I "may" add some nice heads and a better cam, but I think with just the induction opened up, and some better breathing exhaust, I'll be close to where I want to be without any heads or cam swaps.

my goal with out opening the motor was a 12.99 or better slip 300 rwhp and 400 rwtq.

i'm sure it will hit 12's probably 12.8's or better now and very close to the 300/400 setup on the stock TPI.
 
R

rel3rd

Guest
my goal with out opening the motor was a 12.99 or better slip 300 rwhp and 400 rwtq.

i'm sure it will hit 12's probably 12.8's or better now and very close to the 300/400 setup on the stock TPI.

Mad Mic, I know you have been very busy lately, but can you PM me your number again when you get a chance? Thanks bud...

p.s. RAVENS > redskins lol....

Bob
 

Mad-Mic

Gone but not forgotten
Joined
Feb 12, 2002
Messages
1,853
Location
Annapolis Maryland
Corvette
1987 Redskin Red Coupe
Mad Mic, I know you have been very busy lately, but can you PM me your number again when you get a chance? Thanks bud...

p.s. RAVENS > redskins lol....

Bob

Bob,

U SUCK! :rotfl

PM sent
 

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