Cntrvrsy

What would be the ideal intake 4 an EFI small block chevy? I don't like the super ram and the mini-ram looks so small in our engine bay. I was thinking of siamesed runners with a matching plenum. How do u think a set of full siamesed runners would perform? I'm even cosidering converting a tunnel ram 2 EFI. Would that be better than a mini-ram? I'm looking 4 a very broad torque curve (auto tranny) and high rpm capability. I'm looking 4 an alternative 2 the mini-ram.

Vader

Contro,

What you are asking for is the best of both worlds - long narrow runners for low-end torque and short larger runners for high-RPM power and gas flow. The Accel Mini-Ram is a close approximation of this, but still falls a little short on the low-end.

What you really need is a manifold that can change length and diameter to meet engine operating conditions. What you'll end up with is somewhat of a compromise. GM decided to compromise with a little more power on the low-RPM end with the TPI system, since that's where the average driver will realize the greatest benefit. Accel moved the torque curve up a little higher with the Mini-Ram.

The LT1 intake system is essentially a basis for the Mini-Ram. It has shorter runners but manages to produce adequate low-RPM torque, without creating the 4,500 RPM "barrier" of the TPI system. The LS1 induction system is a further enhancement, with longer runners but of larger flow capacity. The low-RPM charging effect is good for the longer stroke engine, and still provides adequate flow at higher RPM. Unfortunately, you can't just bolt on a LS1 intake, and it might not be as well suited to a larger bore engine with shorter stroke.

A tunnel ram is designed for higher RPM power, so while conversion is possible, the results may not be what you might expect.

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Later,
Vader
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"Make Me Bad"
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Jester

What is it with you silly EFI people and your low end? my lowly carbed 305 has more low end that it can put to the ground off the line.

Low end this, low end that.....LOW END SHMLOW END!!!! Get a torque converter.

[This message has been edited by Jester (edited October 22, 2000).]

Cntrvrsy

I know what I'm asking 4 is a lot, but a friend of mines just found out that a guy he goes 2 4 some performance work can custom modify/build intakes. So naturally the wheels in my head started spinning . I don't wanna say who the guy is because his shop is invite only, but he's known, has a webpage even (I checked) and most importantly build engines 4 and races in NASCARs north bush series. Vader, do u know what the runner length of the LS1 is? Thanks.

Vader

Jester,

I know of that which you speak. I have a P.O.S. Holley 4160 on a 355 that will produce way more torque than the tires can handle from 1,100 RPM all the way to the top side of 6,500. I also have a 305 TPI that couldn't beat an egg, but it still turns the 245 tires into smokey little bits from a dead stop, all with a stock converter and 2.77 posi. It just won't KEEP burning the tires as the car gets moving, like a good little SBC should. There just isn't enough overkill.

I'll guess that your engine could benefit at the low end from longer intake runners, but you'd sacrifice power at the top end. This probably explains why there are so many different carburetor manifolds available for different engine applications. A Performer or Performer RPM are better at the low end, while a tunnel ram, Victor, or Dominator are better at the higher RPM power ranges. There is a compromise in any system.

You're right about the converter's ability to get the engine up to its torque-producing RPM sooner. I've often advocated the converter swap as the best "bang-for-the-buck" modification you can do to a car with an automatic. But for the "average" driver with a short list of modifications, a little extra low RPM torque can be useful. That's likely why the LT1 and LS1 have longer intake runners than the average carb manifold. You'd have to admit that they perform adequately for a stock engine with a relatively mild cam profile and small valves. That's exactly what the TPI was supposed to do for the little engine.

For those that periodically venture into the upper regions of engine revolutions, a TPI certainly isn't the answer. For the "average" TPI owner, a little improvement in this are would be nice without sacrificing the benefits of more power from a dead stop. That's why many of us are here, asking the "silly EFI" questions. I thought it was a legitimate question and an appropriate response.

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Later,
Vader
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"Make Me Bad"
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[This message has been edited by Vader (edited October 22, 2000).]