"D" all of the above.

 

Not to the long runners, but efi yes. It was either that intake for the new box intake for the 302 and 351s. I just need something that I can drive everyday in traffic and go lay down some nice times at the track.

 

How about Edelbrock's Performer RPM Pro-Flo EFI #3541 ?

Single plane which looks like a cross between a Vic Jr. and a Super Vic, 1000 cfm TB, etc. It's a bolt on. About $2600 (Summit).



Summit EDL-3541

 

$2600! Kind of kills the budget thing.

I was thinking more along the lines of EDL-2945 or the new TFS Box top intake(it is in the new Summit, but can't find it on the web). The TFS intake reminds me of the Holley Stealth Ram for the sbc.

Are the 5.0/351 intakes as much as a restriction as the TPI intakes?

 

Use the Single Plane EFI intake from Edelbrock and a Elbow with a 75-90mm Ford style TB and you are good to go.

That's what I would do with a 7,000 or higher RPM motor.

Bret

BTW Wine, Beer, and some good Vodka, Gin or Tequlia for me.

 

Use the Single Plane EFI intake from Edelbrock and a Elbow with a 75-90mm Ford style TB and you are good to go.

That's what I would do with a 7,000 or higher RPM motor.

Bret

 

I guess that is something I forgot to mention. This motor will not be turned more then 6500. This car wil turn into my daily driver as much as possible, therefore I don't want to have to run a lot of gear if I can get around it.

 

I disagree with the "long runners and big cam don't match" theory. Here's why:

How does ram tuning occur?

During the intake stroke, the intake valve is open and air is flowing through the runner, port, and valve into the cylinder. About 1/2 way down the stroke, the air reaches max velocity (piston speed is high and valve is near max lift). Then, the piston decelerates, stops, and starts travelling up on the compression stroke. HOWEVER, the intake valve remains open for as much as 1/3 of the compression stroke (do the math). Your favorite Hot Cam closes the intake valve 68 degrees (!!!) after the compression stroke begins. This is because the air in the runner wants to remain in motion (Newton's 1st law). The inertia of the air in the runner still carries it into the cylinder even though the piston is rising.

Now, consider this: ram tuning is more pronounced in longer, smaller runners because both mass and velocity are greater. So, if you close the intake valve early (small cam), you are taking away its ability to use ram-tuning to fill the cylinder during the compression stroke.

So, a longer runner favors a larger cam. Think it doesn't work? The TPI stock eliminator cars have totally stock TPI runners, but cams that are 260+ deg at .050. Mid 11's aren't too shabby for stock heads, compression, intake, TPI.

Consider the LT1, which is basically the opposite. A short runner doesn't allow much ram tuning so, according to my logic, you need to close the intake valve early by using a small cam to trap in as much as possible since ram tuning won't help fill the cylinder during the compression stroke. Now unless something has changed recently, the quickest stock head, intake, short block LT1 belongs to Frank95Z, who has run somewhere in the 11.50 range with the little Crane 210/224 cam.

Mike

 

Mike, you're forgetting that the length of the intake runners affects the rpm at which they tune properly. A longer intake runner tunes best at a lower rpm than a shorter runner, given no changes to taper or runner diameter. A smaller cam also "tunes" best at a lower rpm, so matching the 2 is the best approach if you want to make the highest power in a specific rpm range.

 

What engineermike said makes since to me. Isn't the most important part of ram tuning the 3rd or 4th return wave? Isn't that where all the power is made? This would also support the reason of why the fast 5.0 guys run, what would be considered, a very large cam on a 302.

 

94bird, you are regurgitating the same generalizations that have been passed around for years. Please carefully re-read my explanation.

Mike

 

Not necesarily.

You're leaving out the important stuff. That being the runner length and the effect of runner length on wave tuning (when those waves arrive and which wave will arrive at a given rpm).

If you go back to the original point in this thread, it was about choosing a manifold that tuned at the appropriate rpm for a given engine size and camshaft duration. If you are building an engine to turn lots of rpm and your intake doesn't produce strong return waves at that higher rpm, then the combination isn't going to work real well.
Also, if that wave isn't anywhere near the end of the port and the piston is rising up the cylinder (more pressure in cylinder than depression at the intake port), you will probably succeed in pushing the charge back into the plenum.

This happens at specific rpm ranges regardless (camshaft out of tune with intake/exhaust), but the runner length dictates when those waves arrive and all the studies I've seen show that longer runners tune at lower rpms. That's counterproductive to choosing a cam with long duration, designed to make high rpm horsepower.

David Vizard has published quite a bit of data on this. One test in particular comparing manifolds of just 1" length difference showed the same trend. The longer runner moved the torque peak ~200rpm lower and lost HP up top in comparison to the short runner intake. This was in a 7800rpm engine and here we're talking a change of just 1".



I don't think it's a mater of working or not.... it just doesn't work as well. And on your point, there are LT1 powered cars going low 10's with similar setups and of course a better cylinder head.

Back to your Stock Eliminator example... the fastest of those guys is running close to 10.3 with a cam that most likely closes the intake valve alot later than the Crane 210/224.

By my logic, you need to close the intake valve at the correct time based on the tuning rpm of the engine. You would need an advanced simulation program to do so, preferably with an exact model of the intake and exhaust system. Then you would look at pressure waves vs crank angle and determine when that optimum closing point should occur. Needless to say, that would depend a great deal on the runner cross section, taper and most importantly... back to the runner length.

I'd venture to say that based on data by Vizard and others, that an engine outfitted with a TPI type intake and a camshaft designed to turn 7500rpm, would be down on quite a bit of horsepower and high rpm torque in comparison to that same setup and say, an Edelbrock Victor Jr.

Then look at some OEM's using manifolds that change between two different length runners on the fly. One designed to tune at low rpms (the long one) and the other to tune at the high rpms. They know what's going on.

-Mindgame

 

My explanation was refering to the first, and strongest wave. Each subsequent wave will be weaker and less consequential.

I'm not doubting that longer runners make more low-end. I agree with that 100%. I'm just saying that a long runner intake will make more power with a large cam than a small one.

It is true that a well matched, designed, and engineered combination will produce the best results but, again, long duration cams aren't counter-productive to power when combined with long runners.

Once again, I'm not disagreeing with that. But, the engine outfitted with a TPI intake and a 7500 rpm camshaft would make more power than a 4500 rpm camshaft even though the 4500 rpm camshaft is better "matched" to the characteristics of the intake runner.

Mike

 

I wholeheartedly disagree. A mismatch of that magnitude would result in an engine that wasn't good at anything. I stand by my previous post until you show me dyno results to back up your theory. For now it makes no sense to me.

The only sense I could make of your statement is that you mean from 4000-4500 rpm a larger camshaft will make more power than a smaller one. I guess I say, "So what?" With my smaller camshaft I'll be long gone before the other guy gets into his powerband of a super wide 500 rpm. Now, if you tell me your argument is specifically tailored to drag racers who launch at 4500 rpm, immediately shift to 2nd gear, and then row through 5 gears before the 1/4 mile is done, again, "So what?" The only reason to build a combination like this is if the rules limit you to a combination, such as an intake manifold, that is not ideal. How does that back up your argument that a long runner intake manifold goes with a long duration camshaft?

 

Because it makes more power.

Again, referring to Stock Eliminator TPI motors, a cam of 260+ deg duration would normally make power to 7500, but in a TPI motor, the hp peak would probably drop to ~6000 and shift at 6800. The large cam extends the rpm limit of the TPI.

This may come as a shock to you, but EVERY form of racing has rules that REQUIRE a non-optimal combination of some form.

NASCAR engines have flat tappet cams.

Group B Rally cars have intake restrictors.

SUPR motors have non-ported heads.

Renegade motors run 26 psi boost with no intercoolers.

Etc. . .

If you're starting from scratch and building a street/strip motor, then, obviously, the best results would not come from TPI. But the point remains that "mis-matching" a large cam to long runners still makes the most power.

Mike