Which would be the best MPEFI intake for a street/strip mostly street car. Clifford, Offy, or a custom designed intake? I believe I read some where that someone intended to use the upper portion of a two piece BMW intake with a custom lower to mate to it. I have access to get the custom stuff done. I just want to know which is the best route to take. I've read that in carburated situations that the Offy is best for the street while the Clifford is better suited for the track. But what about for a MPEFI use? For the custom job, what would be the best inline motor to try to duplicate for slant use?

Dart68

I chose a Clifford. It was easier to setup for EFI. If you wanted to get wild you could convert a tripple Weber setup to EFI.

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1966 Signet
Turbo Slant Six

I have looked at the older bmw intakes(the ones that bolt together), because they have nice power, good torque, and are nice to drive...
I wonder why most efi cars have the plenum box over the engine, and 180 degree turns into the head?

Sure, the runners are long, but not all of them need to be bent like that to fit in the car...
Any good reason for the 180 bend?

I am pretty sure the auto manufacturers use the plenum/runner intakes for a reason...

I think the hyper-pak repro intake would be the best. EFI would solve all of the fuel distribution and atomization problems the the h-pak is known for.

I think this would be good for a street/strip car, if you turn the tach up past 4500 the Hpak tuned port effect would diminish I think. The shorty manifold would be better for the high rpm, or direct port injected like the hilborn...

Just as an FYI, the intake I got from Reed was too thin on the top runners to put a set of injectors at a tilt without some massive welding to the casting, and with the quality of the casting there might be some "problems" there too...(that's why Rance and them grab the shorty runner versions with bungs cast into it)...

-D.Idiot

Call clifford - they sold me their standard intake, already drilled out for mpfi, for the same price as a normal version. Apparently they made a limited run of them when they were planning selling an mpfi system.

Hopefully this isn't off-topic and I am not trying to hy-jack this thread but with MPEFI install with the injectors at the end of the runners, how much affect would runner length have since wouldn't it just be the air being distributed through the individual runners at that point? I thought it was always more of a fuel issue with the different runner length (ie unequal air fuel mixture from the varied runner lengths) higher fuel to air for the inner runners lower fuel to air on the longer runners? I thought the Hyper pack issue was the length of runners and the plenum not being sufficiently heated so the fuel pooled when it came out of the carb?

with MPEFI such as the clifford (insert the word intake here ) the injectors are position ~1 inch from the head so pooling would not occur?

Brian

MPEFI takes care of the 'fuel' problem, yes...but intake configuration also changes other factors too...there still are reversion waves bouncing back and forth in the intake you still can have 'ram-effect' with air and no fuel (probably not too much to worry about, but I'd bet at 3500-4500 the fuel map might have to change to compensate for that slightly since the system is not an analog carburator)might affect torque curve and top end performance, most EFI engines now use a longer runner (curved over to make it compact since they only deliver air)...but historically long rams (like the 413 'long ram') had great gobs of low end torque and was good up to a certain speed, yet the Nascar guys ran a 'shorty ram/cross box' because they needed the power at the upper rpm level where the other intake would fall off( plus it was harder to make valve and carb adjustments with the long rams...)...

So for street driving where low/mid range torque is needed and a shift rpm of no more than 4500 is good...no problem....if the guy decides to go draggin and pumps the car up to 6500 he might not get that extra bit of HP past the 4500-5000 range.

There used to be a good article (can't remember who wrote it) that compared intake manifold types... in this case the Hyperpak is very similar to 'Tuned Port' intake types, and the shorty manifold would be similar to the 'open plenum' type (closer to dual plenum if you have the OEM super six setup).



-D.Idiot

The formula to calculate runner length for best ram is 84,000/desired rpm=runner length:

84,000/2000=42 so 42" long runners to take max effect of the ram tune at 2000 rpm

84,000/4500=18.66, so about an 18.5" runner to tune for 4500 rpm etc.

The nice thing with EFI is that you can shape the intake any way you want to get the runner length. Take a look at some of the new EFI cars in the junkyard and you'll see what I mean.

Marc
www.marcmedina.com

That was me with the BMW piece. However, instead of using that, I had a local shop modify a Clifford piece. Reason was that a completely custom lower intake would probably have been even more expensive unless I welded it up myself, and my welding ability is pretty dismal. I still want to try this one sometime if I don't try independant throttle bodies. The manifold has some pretty big runners and a truly enormous throttle body, and I'd get the runner lengths a lot closer to equal than with my current setup.

I believe the bend in the intake was for packaging purposes. It would help on a turbo slant to keep the bends, too - more room for the turbo setup. However, if you don't need the room, a straight-out setup may pose a little less restriction.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair