who makes a good EFI single plane conversion for my L98, plus what results should I expect compared to my Tuned Port?

 

Expect a huge loss in low end torque and driveability;assuming most components are stock your car will feel like a slug. You may gain a bit up top. Unless youi are going all out on a crazy buildup I wouldnt' do it.
Any mods?

 

Holley, Accel, and I think Edelbrock, make intakes with injector bungs cast into the runners. Holley, MSD, Accel, and a few others also make 1,000 cfm 4 barrel throttle bodies. Lingenfelter sells an elbow that lets you use a 2 barrel GM TPI style TB on a single plane intake, as well as fuel rail blanks and injector bungs for welding onto a carb'd intake. These conversions were usually done to large displacement small blocks that were raced more than street driven. However, lately they have been used in street rod/muscle car retrofits on tamer 350s and 383s, intended and tuned for street use. They seem to work best with awesome flowing heads and fairly radical cams (in cars that are considered 'smaller and lighter' than the average musclecar). As with any engine combination, it can make for a nice improvement in performance with the right parts, gearing, and vehicle dynamics (weight, chassis design, trans. type, intended driving style). The key to success would be the programming of the computer, most likely being done, eventually, on a chassis dyno. There would be a loss in low end torque compared to a well thought out TPI based set-up, but it would allow for a pretty healthy power range in a stick car with some 4.10s and an engine capable of 6500 rpms or more. Too much low end torque in a street car on cold street tires is quite often wasted on tire spin and a less than optimal launch. Strong mid-range power and being able to continue to accelerate a car into the higher rpms allows for better utilization of each gear without having to 'fight' the car's street oriented chassis design under hard acceleration. It's up to you to decide how the car gets driven, and that should be the first consideration when modifiying your car.

 

You may want to look at the Holley Stealth Ram. It's relatively new and a few magazines have done write ups on it showing good results. You may want to dial up GM High Tech Performance magazine on the net and do a search for Stealth Ram. I seem to remember they had an article on it.

 

hi all

im thinking going single plane efi , too...

but im also building this on a 396...

car ia a 90 with manual 6 and 3.73 gears...

what would you say ?
slouch at start? beast?

i will definitely go with aftermarket heads, dont know which one for now, but im thinking in the range of 200-215cc´s intake runner volume...

please let me know..

where are good efi single planes available?

regards :-)

 

I, too, have heard of excellent results with the Stealth Ram, on mild engines as well as more powerful combos. I don't think it will fit under a C4 hood, though. Who will be the first brave soul to post pics of himself taking a sawzall to his stock hood?

 

what dou you think about the the holley HLY-9901-101-1 intake
can be found on summit...

summit lists this intake 2000-6000 rpm, on the holley site the say 2000-7000 rpm...id rather believe holley...

what dou you think about...

the stealth ram looks very nice, but i dont think it will fit underhood...

 

There are NO good single planes available on the open market that are good for what your trying to do in the sense of EFI.

That is why we used Edlebrock (carb) intakes in both Super Victor and Victor JR models to retrofit to EFI for our motors.

They are BY FAR way superior to any EFI available intake on the market today.

There are some posting from me back in the developement and testing stages of Jeb and I developing one that would work under the hood of our cars.







This is what is on my car now, but these picture of it polished professionally by a vendor.

 

I have the same exact (more or less) manifold as above, just unpolished. I bought it for a future build and in the mean time I stuck it on the L98. If you're going to have the combo for a long time and aren't planning on much else, like a larger engine in the future,don't do it. I did this purely as a test with the results pretty much known before I even got started.

I have absolutely no bottom end, and my power band shifted way high up in the RPM band. The car pulls pretty good from 3000 RPM and up, but getting there is a chore.

You should also know, the intake will not fit the 113's without either grinding on the intake, or the heads. I ground down the lip on the heads. For the best results out of this intake, I wouldn't use it on anything smaller than a high winding 383. Ideally you'd want 406+ cubes. I have my doubts even then that the manifold would be ideal, I'll find out soon enough on my 406. On a stock application your port velocity is going to be the major suck and you really need some cubes to take advantage of this manifold.

Keep in mind the listed RPM range of this manifold is 3000 to 8000 RPM.

Depending on your desired results, the Super Ram is hard to beat.

 

What have you done to the engine? You might be better off something else like a mini-ram.

Converting a single plane intake isn't hard.. any competent machine shop can do it in a matter of a few hours.

I converted one with a mill I have here at the house in 2 hours or so.

 

That's a nice looking plenum

 

Im thinking about using one on my roller cammed 406 next winter after i swap it into my car, motor is a long rod 406 w/ bowtie heads, not sure what cam i will use yet, Im still concidering all options, it will see some street use and some strip use.

 

Try this for info;
http://thirdgen.org/techbb2/showthre...hreadid=250091

I built one also, but unfortunately I still dont have it done. Life gets in the way of alot of my projects.

 

ski sounds like he has some good experience in this 'uncharted territory'. The Edelbrock Victor Jr. has always been an excellent intake, bridging the gap between a compromised dual plane street intake and the NASCAR looking high rpm single planes. If I were to build one, I would probably forgo an EFI model and use a customized Victor Jr. You can generally drop a carb intake's rpm 'starting point' by as much as 500 rpm when it is acting as a 'dry intake' on a modified port injected set-up. Another option is to add some 'runner length' by using the GM style throttle body on an elbow adapter, but this may create air filter and hood clearance issues.

 

Considering the history of our Dana 44's, I changed my intake from a SR to Jeb's single plane. I have no regrets.

My 60 ft did go from 1.51's to 1.58 but I shift at 6200 vs 5400 with SR and I picked up et of about .08 and 1mph.

If you have the power for it - it is a very good alternative.

There are pics in my corvette photos.

 

the above mentioned 383 vette is one of the fastest all motor street car in the country to boot and gets 20 mpg every day of the week


Bottem end loss???
this past saturday the above mention vette spun hard at the track and lost the round from too much bottem end and that was on 26 by 10 inch slicks not street tires too!!!!!!

 

I'll assume that bottom end loss comment was for me. Please note I was referring to a stock L98 with regards to bottom end torque loss, and not a highly modded 383, which obviously wouldn't suffer from such an affliction.

I would assume on an otherwise untouched L98 you wouldn't recommend this manifold either.

 

You will not LOOSE torque; you will MOVE the powerband higher in the RPM range with the single plane. In fact, generally you will gain both torque and a lot of horsepower; but it will occur anywhere from 1500-3000 rpm higher than a conventional TPI or modified TPI style system.

I have been building and running single planes on C4's longer than just about anybody and here's the issues if you want it to fit under the stock hood which is fairly low at 9.100" from the front rail on the engine block. If you use a Super Victor intake (like I generally use) and a 4v throttle body then you're left with about 1.2" for an air cleaner assembly. I built a killer NASCAR inspired aluminum airbox when I ran the 4v but it was so restrictive that it cost me 5-8 mph at the track but it was fine for the street. The Accel and other mfg's t.b. adapter elbow is also too tall to work under the stock hood with a Super Victor manifold; you have to mill approximately .750" off the carb pad (and sacrifice plenum volume) to get it under the stock hood. The plenum I built to use the conventional t.b. as shown on Jesse's setup above "just" fits under the hood. I would've rather made it more contoured but it's hard to do when you're working with little room, but them's the breaks...

Now, even though I make these to sell I'll be the first one to steer you away from them too... They're not well suited to stock cubes or even mild strokers; but if you have a more radical combination (383+) with a large camshaft they're the best currently available manifold. Unless you're pulling 7k+ out of your 350" motor with huge compression, gears, and solid roller then the SuperRam is DAMN hard to beat; I'm still running one on my wife's '85 383. Additionally, do NOT believe the rpm range of the manifold as advertised by the manufacturer's; they are designed around the belief that they will be used with a carb as a "wet flow" manifold, not an EFI "dry" manifold. Those rpm numbers will not accurately represent your manifold when used in EFI.
-Jeb

 

Which is essentially what I said in my first post. I should've just phrased it accordingly in my second.

Again we're in agreement.

Something else I know, but neglected to mention due to the nature of the question.

I absolutely love this manifold and can't wait to get it on top of my 406 to see how it goes. Being a mild build with a smaller cam and smaller heads I think it'll be a relatively good fit, maybe just a tad too big for this version. The single plane should be a good fit between the SR, where I don't want a ton of torque down low, and the MR, where I don't want to spin the shiznit out of engine to make power.

 

hi..

i think i will go with the accel efi intake pn 74139 on my 396

would you say this will be a good combo with heads around 200-215cc intake

i want to drive this car on the stréet, but i have 3.73 gears in it and it s a M6

thank you