This is the first I'm hearing about this. I've seen some high HP cars with minirams, and I've been told specifically by http://www.built4speed.com to go miniram.

I'd like to hear Jeb's opinion on this too. :confused:

 

My take on the MR is that it's a decent manifold... I've run them both with n/a and f/i applications. The biggest problem with the MR is twofold. It has reversion problems when you use a "real" camshaft...It DOES NOT LIKE overlap! But, neither do most forced induction applications; why blow half your intake charge out the exhaust port?? The secondary problem with the MR is their $h!tty fuel rails... And this is an issue I will NEVER back down from; for the $300+ it costs for TPIS's rails, fittings, and regs I expect a lot better. Most of the MR's I've run I've built new fuel rails to... This solves the distribution problems. For forced induction the MR is a good manifold, particularly for centrifugal cars that need rpm. But, you also need to figure out how high you want/need to turn it becaus you also don't want a lazyazz motor... As was said above positive pressure increases the flow potential of the manifold so whether it's an SR, MR, or TPI (modified or stock) it will support much more power than it would n/a. Personally I wouldn't run a stock TPI, I would rather see a MR, SR, or converted EFI single plane; all of which will make more power overall (both torque and hp).
-Jeb

 

I am glad someone has found out how to tune the MiniRam with a blower. The fuel rail problem is easy to solve but what is done to correct the airflow issue on the miniram with a blower. I am the maker of the Vortech kit that some here are using (first offered in 1991) and was not able to figure out how to get all the plugs to burn evenly with the MiniRam. I would love to see any SpeedPro or DFI files that run correctly. They can be sent to artpaul@opticanetworks.net

 

Jeb,

Can you please help me understand why the miniram supercharged cars don't like a cam with overlap?

I am currently running a nitrous/blower cam with a pretty big overlap with the miniram, and I would like to know what to lookout for.

What I am noticing as of right now is that the big overlap of my cam is only creating 8" of vaccum at idle, the result is a brake pedal that is hard as a rock.

If you can tell me anything else I should look out for I would appreciate it.
Thanks,

Paul

 

:confused: O.k. Now I'm confused. I thought blower cams DON'T have overlap. At least, I thought this was the biggest differentiator between N/A cams.

You could always install a vacuum reservoir to fix your brake problem. They're like $20 from summit.

 

Right now i am running a stock Knock w/stock TPI(and Throttle Body 48MM) bigger injectors 30# fords, and a FMU. I had my chip burned by Ed Wright and need to have it reburned for my 30# ers but what i would do is go to a dyno and do a run and see what your air/fuel is. Also how much boost are you making and what does your fuel pressure read under boost? Then if you are running 12:5 air/fuel then it has to be something else because from what i have read that is about the right #? Then i would pull the connection on the knock sensor at the dyno and see what it makes after your first pull. see if the # are different. Also have you changed the O2 sensor maybe it is not working correctly and not giving the proper # to the ECM?

Tell us what you have done (rear end, EFI, PSI #, Exhaust...etc!) give us all the details so we can get to the bottom of this! :D

 

I was told by the people over at Comp cam's help line and my engine builder both told me that supercharge or nitrous cams should have a big overlap. They said almost word for word that supercharger cam and nitrous cams are the same. Now I am confused? I am not an expert so maybe someone can help me understand all this?

I have the summit catalog but I can't fiind the pump? Do you know where it is in the catalog?

Paul

 

Then either they shouldn't be giving advice, or there is a misunderstanding somewhere. You do NOT want a lot of overlap on an FI motor. You want to keep the intake/cylinder pressurized. If the exhaust valve opens too soon you relieve intake pressure and that defeats the whole purpose. Same thing with nitrous. Why would you want to blow that expensive nitrous out your exhaust anyway? ;)

Also, that's what makes FI motors so streetable. A lot of overlap makes a car very rough at low RPM's, and it's all due to overlap/duration.

maybe our terminology is mixed up or something. I don't know why you're getting the same advice from 2 seemingly qualified people. :confused:

If you're referring to your vacuum quandry, it's not a pump. It's a canister about the size of a coffee can w/ a check valve that holds vacuum in reserve. Go online http://www.summitracing.com and do a search for "vacuum reservoir"

:cheers: :thumbs:


[Modified by vvv90, 7:09 PM 12/31/2003]

 

Woops, double post. :leaving:


[Modified by vvv90, 7:08 PM 12/31/2003]

 

Jeb,
I agree with your assessment of the fuel rail issue on the MR. I contacted TPIS, and they said that the TPIS fuel rails were good to 500RWHP, probably more. I wound up changing the rails prior to installation (and yes, I bought the TPIS fuel rail option when I purchased the MRII).

What is your definition of a "real" camshaft? I run a healthy solid roller cam in my '87, and it pulls 14" at idle. It has a considerable amount of overlap at 27°. I am aware that for a motor producing ~300na HP with a 200 HP power adder (N2O or FI), that you could get away with a cam that had very near 0° overlap. But these "low overlap" cams do not make big power when you are looking to be closer to 900-1000+ FWHP. The cam I run in the '87 is responsive down low, and pulls very strong past 6500 (6700 rev limiter). The MR with that cam has worked well for me after the MR modification.

But, on that same note, I would not use this intake again, if I knew I was eventually going to be above 700FWHP. I would have instead gone the route of the converted single plane (as I have done on other cars).

Aaron


[Modified by AKS Racing, 2:50 PM 1/2/2004]


[Modified by AKS Racing, 9:05 PM 1/5/2004]

 

jburnett, what are you doing to the miniram to fix the flow problem with blowers?

 

Put a converted single plane on it... :D

No, seriously...There's not a whole lot you can do short of cutting the manifold in two and reworking the plenum and port configurations. That's the main inherent problem with the MR and it's exacerbated by forced induction. The short runners and the way they go into the plenum does not allow equal pressure across all cylinders; personally I think this can be corrected in one of two way (both are difficult to do on a MR)... One is by lengthening the runners a little bit and the second way is by increasing plenum volume.

MR's and most other SHORT runner manifolds do not like a lot of overlap; they are prone to intake reversion (air travelling back up through the intake and into the manifold) and it causes a pulsation effect that both hurts airflow and distribution (unequal pulses). A supercharged car certainly doesn't like overlap and if Comp told you that then they need to go back to school. N/A motors for maximum power will run best when overlap is present because the exhaust opening and evacuation will actually pull intake air into the cylinder (a venturi effect) making for a more powerful combustion. However when there is positive pressure from a blower the result is the exact opposite; at the period in degrees that the overlap is present the forced air coming in the intake will push right through the cylinder and out the exhaust thereby wasting a complete cylinder fill... Some overlap on blower applications is okay, but it needs to be minimal so as not to waste the charge; the reasoning behind "some" overlap is that it will be advantageous in ridding the cylinder of exhaust (additional pressure from the f/i will "push" exhaust gas out). On a turbo application you want NO overlap, a very wide lsa usually typifies this... Why? Because it builds exhaust pressure which makes the turbo more efficient.

As for the MR's problems with distribution, the only way around that is in a redesign of it. The fuel rail issue is relatively minor, I usually build completely new rails. But there's nothing that can be simply done to promote better air distribution in the manifold. I haven't played with f/i MR motors enough to tell you definitively what can be done; just what I've observed in the ones I've messed with...
-Jeb

 

What would you recommend to run instead of a miniram for ~800FWHP F/I applications on an LT-1???

 

Not always true on the turbo setups. If you have done your homework designing your system, you will achieve crossover (the point where intake pressure is higher then exhaust, sometimes by a lot). At that point the motor really doent even know that the turbo is there, and camshaft needs are much like that of an atmo motor. I run a 219/228 on a 112 with my giant single turbo, and it works very well. The conditions your describing are for your typical "street" setup with small twins or gn's where the hot side pressure is twice the cold side. they do this for an early boost threshhold, at the cost of top end power. With such a setup overlap kills power because of said reversion and overlap is critical. The size of your turbo has as much an impact on camshaft as camshaft does on torque converter.

 

I figured that out a long time ago. If any experienced members want a copy of this manifold (plenum and rails) for cost (appx. $500.00) I can be reached at 410-984-1001 if you want one.

OK now I am confused. I posted this:

“For a blower car I would never run a MiniRam. I did and have the bad taste from the distribution problems. People I know that have been tuning for almost twenty years won't touch a blower car with one.”

When a member asked about my post, the reply was


Maybe I am missing something but can this thing be tuned or not? I don’t see it working with a blower but that is me. I am guessing from the reply below that it is not a good choice as I has originally said?

 

That's kinda funny...I've been building these for about 8 years now and am just finishing a complete bolt on setup for C4's... Do a search in archives and you'll see what I've done. I should have some more pics up in a few days.
-Jeb

 

Blown Vette,

I can attest to Jebs building of the single planes, having tested one, with great results on the previous 406 motor I ran. I am also planning on running one on my 434 combo.

Why are some of the areas of your picture blocked out? Its not a secret that the manifold's T-stat housing needs lowered to clear the TB :skep:

Also I have seen other renditions of the convertered single plane elsewhere as well. Some better some downright laughable. Like this one.



I did not have the heart to tell him his injectors are not aimed at the back of the valves. But to each his own.

I can attest that Jebs unit was a nice piece with all the fix'in that will be sure to perform.

My .02 about the MR and my tuning experience and personal observations are I have seen 1 car improve ET with the addition of it, and it was built for a MR setup, but running a SR to start off. What i mean is it was big CI, big gears, higher RPM, and big heads, so I would expect nothing less than a gain. However the majority of cars I see add a MR, loose ET and report problems. For me the SP was the best compromise between the two. It performed equally was well as the SR, with a bunch of details of the setup not fully optimized for the SP. It has my :thumbs:

 

yes i do remember seeing that pic on thirdgen.org in the tpi section...i am in the process of siamessing (<--didnt spell right :lol: ) the intake and running siamessed runners and porting the hell out of my plenum.

BUT before i do all that i want to do a dyno run (or 3) so i have a consistant # then do my port work and do an after dyno run :D

 

Anyone else have pics of a cool intake?

 

I was really looking for an answer on the Miniram tuning, but you are right that I blocked out some areas I spent a lot of time making work.

You would be surprised that someone would look at a picture like you posted and copy it as a working example. Anyone that knows what they are doing knows not to use a square box as a plenum on a single plane manifold.