How big gain can I expect with a Superram on a stock L98?

I am planning on building a 383 with a Superram, but I can't afford to do everything at once, so I was thinking of buying a Superram now and do the cubes/heads later.

The car is a 91 with Hooker headers. If I buy the SR I will buy the base manifold aswell.

Thanks in advance
:cheers:

 

Cratzy,

You sound like me a year ago. :lol: Just want to start buying stuff, then it got out of hand. :crazy:

You will definately tell a difference. Now it sounds like you already did your research and you probably know that your heads will be the next big bottleneck. If I were you, I would opt for the 219 cam, some porting, and some spring upgrades for your heads. Then you will be really able to realize the power and you won't have to rip the intake off again. :p:

One thing I would also recommend is the pop-up style lifter so you can change the cam without having to pull the top off the engine.

I have never had any experience with them, but the next time I take the lid off mine, which may be soon, I am gonna try them out. If anyone here has a bad opinion of them, please step in and correct me.

But all in all, you will definately like the SR. ALthough I am still working the quirks out of mine, its a million times more powerful than stock. Also you can see many combos running here that really perform. I hope to soon join the ranks of these fellas.

Good luck, if you need anything let me know.

 

The good news is that your 1991 Cylinder Heads are good for about 350hp without being touched, so that at least allows you to wait a while longer if you feel the need to.

You have already removed 1 of 2 of the biggest restrictions on the L98 with your headers. Good going there! The other is that 305ci TPI intake.

I would expect a superram & header car to be virtually at the doorstep of 12s if not into them very very high. If you spend the extra $300 or so USD and pop a cam in there while the intake is off, you'll be screaming. :)

 

It definitely removes that "wall" at 4500rpm and if you polish it it looks sweet too :D.

I'm having a few issues with mine but still need to spend some more time to pinpoint the problem. Should be hooking the scanner up on Thrusday to see if its anything obvious I can pick out. Mine starts and runs straight to 1800-2000rpm (without any throttle) before dropping down between 1000-1500rpm. Runs fine under throttle it just doesn't to idle properly too much now.

I did the SR now as an experiment now but plan on including it in an engine build later. I think I will try dyno it this week sometime just so I can get the before and after wthout tweaking runs out of the way to get an idea of exactly what the SR does without other major mods. Then I can get bogged down into getting its manners back.


[Modified by Red 90 L98 Coupe, 3:00 AM 8/28/2002]


[Modified by Red 90 L98 Coupe, 3:00 AM 8/28/2002]

 

Red90

Do you have any dyno or track results with and without the SR ?

I would love to install a SR before I do Heads/Cam.

Vic

 

With the headers you have now, you should run very low 13s or high 12s with the Superram.

I would get the 219cam, port your current heads, port the SR runners and base. Then you could definitely run low 12s.

 

Vic, I dynoed it just before I did the SR install (main issue is that most of the dyno operators printouts give you the power at road speed at the rollers - in kilometres per hour instead of engine rpm - not that we couldn't calculate rpm from that though I guess). I held off posting the before sheet here until I had the SR installed and did another dyno run for the after results. I will call today to see when I can book it in for the dyno run.

I have before dragstrip timeslips but no after slips yet, we have drag meets every second or third Wednesday night and I plan on going to the next meet before I start altering anything with the tune. All I will be doing until I document any change in power with the SR is hooking up the diacom, I'm not going to alter fuel pressure, timing or anything else like that until I get some dyno and drag runs in. I figure that is the best way to see exactly what difference an SR will make - if anyone disagrees with my thinking, let me know.

 

I would love to see some numbers on a stock engine with just the SR bolted on.

So you guys think that I can run a low 13's with just the SR and headers? That sounds too good :D

My best run so far is 13,91 and that is with the headers on (2,59 gears). Perhaps I wont be able to run low 13's after all, that is almost 1 second gain, sound too good :confused:

:cheers:

 

I think the 2.59 gear has a lot more to do with it than the SR will.
If you want to save money and get max performance by doing a little at a time, why don't you go to a 3.31 or 3.45 gear and siamese the stock intake? I think you will get a better gain out of that.

Look at Hole Shot...running a 383 with a siamesed TPI intake with as&M runners, headers, ported stock L98 heads, K&N filter, 219 cam with a stock computer chip, a 3.45 gear and a shift kit....and he's running 12.1-12.2's in the 1/4 mile.

So, with a little grinding the TPI works great, even on a 383.

If that isn't a good case as to why you do NOT need a super ram, I don't know what is ( the SR is definitely not worth it for what they cost ).

 

I put mine on the stocker for a few weeks while the other motor was gettin' finished. You _will_ be faster, it just won't feel like it. The motor pulls about as hard, it just CONTINUES to pull waaay past 4500 rpm.

Holding the tranny back, It'd pull to 6000rpm (Tranny at WOT wanted to shift at 5200 rpm)

 

Now that you mention it, I haven't really tried to spin it that hard (to 6k) yet - I think I will wait until the dyno run, the dyno operator will back off when power drops so I will see what the findings are there before spinning it that hard. I didn't try going that far yet because of mechanical sympathy and I didn't think it would make much difference spinning it that hard because of the stock cam I'm running.

Weather permitting, I think I'll be going to the track next Wednesday... http://www.eastern-creek-raceway.com/home2.htm



[Modified by Red 90 L98 Coupe, 3:42 AM 8/29/2002]

 

More RPM's = more Horsepower. see http://www.vettenet.org/torquehp.html for an excellent description on how HP and Torque relate and power is made.

 

Very interesting reading - but what gain in hp and/or tq will I see on a stock (with Hooker headers) L98? :cheers:

 

Agreed about the interesting reading. :cheers:

Mines booked in for a dyno appt on Monday @ 8.30am (our time, we are about 12 or so hours ahead of you guys), I will do my best to scan the dyno printouts and post them here that night.

Note: I have stock exhaust manifolds and the B&B is catback only (one cat system) (I know that is probably my next restriction in the car but I won't spring for pipes until I decide how far I'm going with the motor - I don't want to buy two sets of pipes).

Anyway, my results should give a ballpark indicator. Funny, I haven't told all my Vette buddies over here about the SR thats now on my car but I'm posting dyno sheets on the web. :crazy:

 

Anxious to hear your results. My experiences weren't so good with the SR on stock heads/cam. The car seemed to pull harder, but as a result of making more torque, the tires never hooked at the track. I went from a best run of a 13.7 to a best run of high 13.9s. Not the right direction. :-)

I did have similar idle problems to the ones being described on this thread. I suppose that's one of two things, either a vacuum leak, or the fact that the plenum of a superram acts like a capicator for air and the engine doesn't know what to do with that much air.

As a result, the car is now going through the whole top end as well as a D44 conversion on the rear end.

I think that all of the problems will be gone then.

Ron

 

Ron, but what happened to your mph? I know you said you lost et but did you make enough runs with both to compapre mph with the SR? If it was higher then its a matter of traction, not the cars fault.

I'm looking forward to the results.

 

Could all of this kind of stuff be done to my 85. superram and what not. is my l98 the same as all the other l98's or what?

 

Your 85 has one thing all other L98s do not have..... TRW Forged Pistons. This is a good thing!! :yesnod: :D Yes the Superram and other components can be installed on your engine. One thing you must remember if you change the camshaft in yours is that your engine is not a rollercam engine.

Ralph has a SR (and more) setup on his 85. Runs in the mid to high 11s. :eek:

 

Red 90 L98 Coupe, no offense please, but I have to disagree about getting dyno runs with the SR before you tweak the FP.

Presumably your FP was set to optimum to match air flow for the prior pulls and should be for the next set of pulls.

Afterall, the AFPR is just a tuning tool, by itself it adds no air flow; it only matches fuel to increased air flow. And increased air flow is what we are realy about; once we get the air in there we can always add more fuel.

It will be very interesting to see your new & old dyno plots.

BTW, if you can get some time slips before & after the SR goes in we can use trap speed to estimate HP gains even before you get the dyno pulls. Assuming you launch with about the same amount of fuel, etc.

 

I hear you 65Z01, no offense taken whatsoever. :cheers:

Here is the problem - when I did my before runs the tailpipe sniffer on the dyno said I was way rich with a 10.8 A/F ratio (after the cat) with an average of 224rwhp over two runs (220hp & 228hp). I chose not to spend time tuning it because I would be spending more money on dyno time tuning a setup I was not going to keep using.

I have an AFPR but didn't use it as a tuning tool on the dyno, I knew this was the best way to use it but really did not realise just how much effect the slight bump in fuel pressure I gave it would have on the tune of my car until my first dyno run (the "before" test here). Lesson learnt - I just hope the dyno runs will retain some relevance even with the car being rich.

I have about 19 hours before the dyno run, at this stage I was planning to go there with the fuel pressure as is, and see what my A/F ratio is now with the different intake to try keep all other factors as unchanged as possible to minimise the chance of other changes effecting the "after" results. I was planning on tuning it properly after this dyno and dragstrip run to optiise the setup as well as trying to eliminate the idling problems I have now.

If you or anyone else thinks there is a better approach to maximise the chance of these runs being useful as a before and after SR comparsion let me know.

I plan on going to the track this coming Wednesday (assuming the weather holds out). I intend on running the same fuel level as always and at first the same launch rpm and at least for the first run using the same shift points. At best I will get four to five runs in. I'm not sure where I should be shifting now though and am hoping the dyno will help me with that. I am worried about traction though - fingers crossed. :)