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Hey all, it has been quite awhile since I logged on to TGO due to well... LIFE. However, that doesn't mean I wasn't tinkering. Currently, I have been carefully "tip-toeing"
around my 1988 L98 GTA with approx. 68,000mi on the clock. After much deliberation, I decided to throw some premium bolt-on's to the L98 to give it the nice healthy
pounce these cars deserve. My intention was to always return the car back to factory equipment in a weekend to "preserve" the time capsule.
Currently sits as:
L98 083 factory heads, fresh valve seals
Dyno Don 1 3/4" Ceramic coated shorties w/ AIR
N10 Dual Y-pipe Cat conversion with N10 heat shield
Flowmaster universal Hi-flo cats w/ AIR
Port matched TPIS Big Mouth Intake Base
Port matched Arizona Speed and Marine LTR's
New Delphi 22lb/hr Injectors
Accel Remote Coil and Cap
ACDelco 8mm Plug wires
On a factory tune! Without any data, the car loves everything done. No issues from what I can sense. I'm afraid I "could" be lean in spots.
Tuning experts please feel free to chime in, I'm not opposed to pursue data-logging and sending the info out for a memcal, but I wanted
to see if I could get away with running the factory tune with the appropriate injector.
Currently, I'm battling a very crappy weld job done on the N10 install, but that's an easy fix. Ill find a shop that will let me on the floor.
Lastly, a lot of lessons learned with "potential" warpage or just a manufacturer flaw on the AS&M LTR's, causing me to chase a intake leak
at the lower runner flange near the cold start injector. I got tired of taking it apart, so I used a equivalent to the Threebond 1211 sealer, which
was the Versachem Type II. The car loves closed loop, and runs very cool.
As much as this post is with getting reacquainted, I wanted to pick everyone's brain on those bolt-on's listed on a factory tune.
Also, speculating the power to be around 275ish rwhp, torque to be nice, flat and chunky. It definitely chirps at the shift points!
Anyway, here she is!
Last edited by TPI; 05-17-2022 at 10:29 AM.
Reason: Dressing up the paragraph layout
I wouldn't think 275 rwhp. At the crank maybe. Looks great though.
Thinking the N10 upgrade is about 245hp rated, Big Mouth and AS&M’s net around 20hp or so, Dyno Don’s got be at least 10 to 15.
Fresh Delco plugs and the Delphi injectors really make it respond. Don’t plan on throwing it on a dyno, unless I dig into it alittle bit more!
So you are probably right in that regard!
Only a speculation, or wishful thinking! Really don't want to throw much else at it, too intrusive.
Last edited by TPI; 05-17-2022 at 02:27 PM.
Reason: Puncutation
Wondering what else I could possibly throw at her with cracking into it too far. Id hate to yank the heads on a very young L98,
but I am also aware that is where we pick up the most power with heads, cam and valvetrain. I'm thinking she is fine where she is for
what I do with the car.
I don't feel the current combo is good enough for 275-RWHP, that's not to say you're not making that, I just don't see that number looking at the mods; stock cam, springs, heads, etc. Your 22# injectiors are good for 280-FWHP at 80% DC. If we consider you're making in the range of 275-RWHP, then that would be about 350-FWHP (roughly), which already makes your 22# maxed out at 100% DC. So you'll definitely want to make sure you're not running Lean anywhere if you're making those numbers. For what you're looking to do with the car though, you don't need extensive tuning. You didn't touch the cam, you just increased plenum volume which raises RPM range. An AFR gauge will tell you where you are at idle during Closed Loop at operating temp, and that is all you really need to know. If it is higher than 14.7, then get yourself an adjustable fuel pressure regulator, and increase fuel until you see an average of 14.7 AFR. That's all you need to do, because again, you didn't touch the cam, so the VE table has merely been raised, doesn't need to be re-configured...
From there, just get yourself a 2400-RPM stall speed. You'll be good to go...
Thinking the N10 upgrade is about 245hp rated, Big Mouth and AS&M’s net around 20hp or so, Dyno Don’s got be at least 10 to 15.
Fresh Delco plugs and the Delphi injectors really make it respond. Don’t plan on throwing it on a dyno, unless I dig into it alittle bit more!
So you are probably right in that regard!
Only a speculation, or wishful thinking! Really don't want to throw much else at it, too intrusive.
Originally Posted by Street Lethal
I don't feel the current combo is good enough for 275-RWHP, that's not to say you're not making that, I just don't see that number looking at the mods; stock cam, springs, heads, etc. Your 22# injectiors are good for 280-FWHP at 80% DC. If we consider you're making in the range of 275-RWHP, then that would be about 350-FWHP (roughly), which already makes your 22# maxed out at 100% DC. So you'll definitely want to make sure you're not running Lean anywhere if you're making those numbers. For what you're looking to do with the car though, you don't need extensive tuning. You didn't touch the cam, you just increased plenum volume which raises RPM range. An AFR gauge will tell you where you are at idle during Closed Loop at operating temp, and that is all you really need to know. If it is higher than 14.7, then get yourself an adjustable fuel pressure regulator, and increase fuel until you see an average of 14.7 AFR. That's all you need to do, because again, you didn't touch the cam, so the VE table has merely been raised, doesn't need to be re-configured...
From there, just get yourself a 2400-RPM stall speed. You'll be good to go...
- Rob
Hindsight, more than definitely overshot power to the wheels. Its been awhile, but I feel like all the ingredients are there, responsibly of course.
Stall is probably a great idea, and easy enough to swap in. I'm going to put a few miles on it and investigate the A/F ratio, she may be right on the
money.
Definitely just trying to capitalize on the strengths where possible!
Don't get me wrong, I'm not here to say who is making what... it's just after tuning countless L98's and LB9's over the years, a cam and heads are worth the most overall NA. We can increase plenum volume and rev the engine higher to make more power of course, but then it becomes a question of the stock valve springs... if the valves are floating at higher RPM's, then you're not really reaping the benefits of an increased intake volume. In the end though, your AFR will tell you everything you need to know. Rich or Lean, as well as how much Horsepower you're making...
Don't get me wrong, I'm not here to say who is making what... it's just after tuning countless L98's and LB9's over the
years, a cam and heads are worth the most overall NA. We can increase plenum volume and rev the engine higher to make more power of course, but
then it becomes a question of the stock valve springs... if the valves are floating at higher RPM's, then you're not really reaping the benefits of an increased
intake volume. In the end though, your AFR will tell you everything you need to know. Rich or Lean, as well as how much Horsepower you're making...
- Rob
I'm in the process of gathering up some data logging equipment and associated hardware. My "would-be" tuner is offsite requesting a datalog, wants a closer
look at whats happening and deleting the cold start injector. Although, I'm eventually working my way toward tuning myself for future builds involving OBD-I/II.
Ill more than likely reach out to Tuned Performance, since he is pretty helpful to everyone on multiple different sites!
Running a wideband definitely has peaked my interest, but I need to self educate a bit more if I go that direction.
Please everyone, feel free to chime in with any thoughts or opinions. Just getting reacquainted with the boys!
Last edited by TPI; 05-19-2022 at 11:07 AM.
Reason: Formatting
With a stock cam, stock heads, stock tune, you're likely making close to the factory rated power levels. Speculating about how much power this and that adds is a fool's errand, just take it to a dyno and get a real baseline.
There are probably a few easy ponies left in it with a more aggressive tune and perhaps some 1.6 roller rockers. If you want to wake the car up further, a higher stall converter and shorter rear gears would help.
05-17-2022, 10:26 AM
