Superram going onto mostly stock L-98 what sorta gains can be expected?

[XtremeVette]

I was thinking about upgrading my plenum to a superram and getting the superram runners as well.

On a mostly stock except for bolt-ons, exhaust, and open air lid L-98....what kinda gains might I expect?

Think its worth it? I know that later on down the road once I rebuild my motor and stroke it to a 383 that the superram will really open it up, but was curious as to what it might do to a mostly stock car.

 

[vader86]

Hard to say, you could run into a problem of tuning, its going to be delivering air differently than the TPI would.

I would expect some nice gains, but I think I'll have to defer to someone who has specifically tried this to say how the car runs and idles.

 

[surferdave]

The potential for gains are good, but that alone won't get a whole lot. Add larger throttle body, some port work and a cam/lifter set up possible headers to let it flow and you may get 80-100hp. Every little bit helps.
dave

 

[rrubel]

Just FYI, if you get the plenum, you HAVE to have the runners. Not sure if you knew that by the way you phrased your first sentence...

The stock manifold is a bit of a bottleneck, and so is the 48mm TB if you're drawing into a SuperRam. Just replacing the plenum/runners, I wouldn't expect more than 30-40 HP, tops, and a lot of that would be at the high end of the rev range. John Lingenfelter, in his engine book, says he got 65 HP on a 383 with just the plenum/runners, but that was all above 5500 RPM. There was a slight drop in torque around 3000-3500, because of the shorter runners.

LPE told me that with their 219 cam, full SuperRam plenum/runners/base combo, headers, and some decent heads I could get 400-450 HP and similar torque from my 350. That's about 200 HP and 70 lb-ft improvement over a stock 86 motor. Of that, I would guesstimate that half is from the heads/cam and half is from the intake setup.

Hope this helps... I'd recommend you read a copy of Lingenfelter's "John Lingenfelter on Modifying Small-block Chevy Engines" before buying anything. It's a great book, and I wish I'd read it sooner.

[RICHR]

 

[Edmond]

I think someone said that TPIS was blowing out their Big Mouth manifolds for $390 or so on eBay.

Our TPI intakes were designed for the 305 motor back in the day so it's a big choking point.

Just wait a little longer and change the intake while you're at it.

How about a set of 1.6 roller rockers? That would give you a little more lift and less friction so you'd get a few more ponies there.

The SR was designed as a mid-high RPM power maker, right?

 

[Mad-Mic]

you won't see alot of gains and you will see alot of loss on a stock motor. what i mean by this is your HP will gain probably 30-40 HP but will drop about the same in TQ and on the dragstrip this pretty much negates any claims that your car will go faster. it *might* actually go slower due to the cam and heads not being able to flow or i should say *pull* the air thru the motor. we all know the internal combustion engine is a big air pump but lets throw it into perspective. take a stirring straw and blow through it. now open your mouth as wide as you can and exhale. very easy to do compared to the little stirring straw. there has to be some kind of happy medium for the engine to be optimized to flow the more air. if it doesn't it will choke down like it wasn't getting enough air. this also plays 2 fold. if you add the SR and do all the Intake mods to make it breath better but never touch the cam/heads and or the exhaust with LT headers, this actually throws the equilibrium of the motor off. this means basically taking the analogy of the straw test and putting that little straw on the end of a piece of 2" pvc 3' long and blowing in that. yes it will be easy at first till the air hits the straw then it's choked up again. same if it was vice versa. the cam is too small to utilze the SR setup also. the stock stuff is good to 350ish chp but that won't be seen even with full bolt on's. with that being said since you are going to do a rebuild anyway, DO IT ONCE! the SR isn't for the novice mechanic. it's a PITA to get it all working right and you'll probably have multiple tear downs.

Just ask Rich

BTW the stock 48 mm TB is good till 11's so save yourself a few bucks until you do the stroker and go with full bolt on's first. headers and a good exhaust will give you the gains of a super ram or mini ram for that matter until you do the cam and heads then it will start singing as it should.

 

[SPANISHVETTS]

Hope this helps... I'd recommend you read a copy of Lingenfelter's "John Lingenfelter on Modifying Small-block Chevy Engines" before buying anything. It's a great book, and I wish I'd read it sooner.

:BOW Don´t leave home with out it.:bash

I agree with Mic. I have the Big Mouth setup on my 383 and it works great with 3:08 rear gears. My motor was built for Torque not top end even with a 52MM TB the beast runs out of breath just after 5000 RPMs we played with a Super Ram and the engine pulled strong right up to its 6200 redline but felt dead until 3500. Since most of my driving is between 2000 and 4000 RPMs I went the lower Peak HP, wider – lower Torque curve route. The engine has been in the car for a year now with out a single major problem and with the 3:08s I still get good gas mileage.



Do a quick search on this Forum as see how many problems members are having with their MAX HP motors and the rear gears they need to get the power to the ground.:eyerole

Instead of throwing parts at the L98 decide what you want and build the engine from air filter to exhaust tip in one go. You will save money and have a better beast in the long run.

 

[XtremeVette]

spanish....you have me confused!?

Hi...thanks for all the replies and Iam now getting a better understanding.


Spanish....you say that your motor feels dead in the 2000-3500 rpm range? Was this your 350 or 383 and was it before or after the superram? Also you say in one breath your motor was built for down low torque but claim the superram does not start pulling till after 3500?

sorry but you have me all confused...are you liking your superram setup, or not liking it?

 

[Edmond]

I think Spanish said that he played around with the SR setup but he currently still runs with the TPI setup. 383's are all about torque! Combine that with the TPI setup and you're going to roast some serious rubber.

 

[vader86]

I think most people are liking their SR, but the way you phrased your question indicates that you only want the plenum/runners and nothing else right now.

Most who have the SR, also have the TPiS or Accel base and have changed their cam. Very few put the top on without doing the rest, which is what you should do.

At that point you can have a chip burned and not have to worry about any tuning problems.

 

[WhalePirot]

DO IT ONCE! the SR isn't for the novice mechanic. it's a PITA to get it all working right and you'll probably have multiple tear downs.
Just ask Rich

or ME! BTW, some seasoned mechanics don't want to work on them either, due to the 16 1/4" 12 point bolts which require one more wrench than you have in your toolbox to install, plus extra dextrous fingers and a lot of patience. Torqued? HA! UR lucky to be able to touch them all!ad

My 406 pulls quite hard from 200RPM thru fuel shutoff at 6300 RPM. I broke the (early design) stock Dana 36 rear end, as mentioned, without even trying or playing hard. :eyerole

I, and a local Vette pal, had sealing problems with the Super Ram and I swear that it will not go back on, if it ever comes off. There are plenty of comments upon this if you search the forum. Additionally, ACCEL was replacing the cast plenums with billet, due to lousy quality and leaks. If you insist on using one, buy a new tube of RTV black and use it all to seal it. After it dries, you can doll the intake up by slicing of the excess sealant.

The torque characteristics are as described above, with the SR besting others at higher RPMs. Again, as I and Spanish say. Do it once and design a package, with an expert's (one) help.

 

[rrubel]

WhalePirot, where exactly were your sealing problems on the plenum? I'm still getting a vacuum leak that I haven't been able to track down.

I did, however, take the advice of some other SR owners and now the front three passenger and rear three driver inner bolts go down from the top. MUCH easier to install/take out: you don't need to remove the distributor cap or throttle body, and every bolt is accessible.

Tell me more about this cast->billet replacement... something Accel was doing as warranty exchange, or what?

Thanks.
[RICHR]

 

[WhalePirot]

Once, I had info about the billet. I'll have to see if it's still in the folder, as I lost interest in ]it after sealing the lid.

I squirted WD-40 around potential leak areas with the car idling to find my leak(s). One seemed to be at the RF runner/intake. The plenum cover took lots of RTV to seal. I trimmed the exposed excess with a knife after it dried, but cannot attest to what the innards look like.

One possible mislead for me was the 9" of vacuum, which I thought was a leak. Turns out, it's the camshaft overlap, which took me away from vacuum assist power brakes and into the hydro-boost!

I toyed with installing the bolts from inside the plenum, but opted to stay with the design and taught myself some new four letter words as a side benefit.

 

[rrubel]

So you found that the plenum gasket wasn't good enough? Did you notice any leaks around the bolts? I'm concerned; I didn't use any sealant when I installed the bolts in the plenum.

I had the ultimate vac leak... I was sent two left-side runners in my kit so the EGR ports on the manifold didn't match the ports on the runner on the pass. side. Leak city!

9" of vac? Wow. I'm getting 14 at the LOWEST, and more like 18 when the idle settles down. But I still get a fluctuating idle when I start the car and it takes a good while until it begins to settle down.
[RICHR]

 

[SPANISHVETTS]

Hi...thanks for all the replies and Iam now getting a better understanding.


Spanish....you say that your motor feels dead in the 2000-3500 rpm range? Was this your 350 or 383 and was it before or after the superram? Also you say in one breath your motor was built for down low torque but claim the superram does not start pulling till after 3500?

sorry but you have me all confused...are you liking your superram setup, or not liking it?

I am running the TIPS Bigmouth and large runners with a ported TPI plenum and 52 mm TB with a mild cam from GM Performance and 1.6 roller rockers on the 383, not the SR. I had the same setup (different cam) on the 350 which produced almost 300 rwhp.



I have an unfair advantage because the engine builder (Frankie) is a good friend. He races GT cars on a limited budget and through the TEAM I am able to help him out with tires, tools, etc., in exchange I get to try before I buy.



BTW the Team just wrapped up the 2004 F3 season by dominating the class. We are for the 4th year in a row the Team Champions and Driver Champion for the 3rd time in 4 years. The party is Wednesday…do not expect any sense out of me before the weekend.

 

[WhalePirot]

the plenum gasket wasn't good enough?

frankly, I'd wanted to put it together just ONCE more.

Did you notice any leaks around the bolts?

No.

I was sent two left-side runners in my kit

Good grief!

9" of vac?

Yup. Nice cam.You think there is some overlap? Lumpy idle, as it should be, too.

I still get a fluctuating idle when I start the car and it takes a good while until it begins to settle down.

My guess is the ECM is trying its best to make the car run the best it can. Until you get the chip dialed in, expect little better. Mine hunted from 800-1800 RPM until I got the custom chip.

 

[rrubel]

My guess is the ECM is trying its best to make the car run the best it can. Until you get the chip dialed in, expect little better. Mine hunted from 800-1800 RPM until I got the custom chip.

Oh, man... I hope you're right! I've been letting the car sit until I could check for more leaks, but if it's "just" the ECM then I can jump straight to getting a download of data for Jeff to reburn the chip.

I'm still debating now whether I'm going to pull the top of the plenum off again and put sealant there like you did. It seems like a safe precaution to do that.

Thanks.
[RICHR]

 

[WhalePirot]

Tuning is still a bit artsy, I think, and it is all tied together. Injector size, fuel pressure and ECM pulses all are integral and interrelated, of course. Different tuners like different approaches, but in the end, the engine pumps a certain amount of air and the ideal fuel/air ratio dictates how much dino-sauce needs to go in. Larger injectors quirt more fuel; all else equal. Higher fuel pressure, likewise. The ECM will trim out any excess, within its authority, or add(+/-128). The tendency though, is to need to trim out fuel, due to the low manifold pressure resulting from more aggressive cam profiles, which 'tells' the ECM that the throttle is open more than it really is. Hence, the car runs rich.

My sequence was: choose injectors given expected engine power; adjust to normal factory fuel pressure; have data tables in the ECM programmed to centerpoint, so fuel trim values are zero.

The basics HAVE to be okay before the computer is involved, i.e., vacuum leaks gone and other 'old-time' tune-up items are in order, including valve adjustments, plugs, wires, etc. Be careful of running too long and too rich, Rich (I couldn't resist). The excess hydrocarbons can foul the cat and ruin the oxy sensor.