I tried searching for this topic so if its been covered before I am sorry.

Has anybody used a 4-7 swap cam on a TPI motor? What were your results.. I plan to dyno the new motor I am building but I just wanted to know what kind of increases or benefits I can expect.

I am working on a 454 Small block, Stealth Ram, Gen7 box, AFR 210 heads about 9:8:1.

Thanks,

Mark

 

Post your results. My buddy is building a combo very close to your own. He is considering a 4,7 swap himself. Good luck

 

I was thinking of that myself, but I heard that it can not be done on a TPI because of the way the computer and injectors are set up, I never exactly seen it done, but thats not to say that it cannot be done, i'm sure your going to have to burn a new chip so the computer knows what your eninge is doing.

I never really looked any further then that i'm not too much into the computer aspect of the car, if it works please post it becasue I like to see if it works and what horsepower gains you get.

 

The computer wont know the difference.

 

what is a 4-7 cam swap

 

you swap the firing order around and 4 and 7 switch places.




TPI is batch fire. it doesnt know. it doesnt care. it works fine.

i have yet to see or hear of any gains that can be directly attributed to the 4-7 cam... but i dont hang out with circle track guys.. and they're the ones that do it the most from what i understand.

it wont hurt, but will it help? i dont know if you'll see any gain.


if you really are Mr moneybags though, try a identical cam profiles, one swapped one not and post your results. i would be intrested in that

 

As I understand, the 4-7 swap cam is designed for, and only effective on intake manifolds with shared runners (single plane).

 

That was my understanding also about a single plane manifold but I also heard it helped with crankshaft deflection and harmonics..

I will have this on my Superflow dyno and can test different cams.. just not sure if its worth the money to buy 2 cams with the same profile, one regular one with the 4 7 swap, maybe COMP will help me out with this test.

We just put one in a stocker class motor and it has a much flatter and longer torque band over other motors we have done with the same setup, so that is one plus.

A Alky drag motor we did also had a flat torque band with the 4-7 swap, I am just looking for outside input before I invest the extra cash.

 

Even if you were using a sequential setup it would be easy enough to just swap injector connections.

I doubt that you’ll see a measurable difference on a TPI. Between the long runner/plenum setup and the relatively low hp and not much rpm, you’ve pretty much done everything you can to hide/mask any breathing and harmonic effects that you’ll get. I’d be very surprised if you could document more then 5hp difference.

 

When GM designed there Small Blocks they had the idea of the motor running smoothly. When you switch the 4&7 its has to something with which pistons are at TDC and so by switching it you can notice a 15 HP gain by just switching the cam itsleve, no change in lift or duratoin. I have an old maginze that i found that i read that in.

 

is that at the wheels or at the crank?

 

it didn't say
i'm guessing at the crank

 

We did some more dynoing with a std and 4-7 swap cam, very similar duration within 3* of each other and same lift at the valve. The rules for this class are very specific so they both run junk *** 441 casting # heads, 175 of cranking compresion, stock 4 bbl intake, 4 valve relief flattops nothing special at all. The only difference between the two is a Double roller timing chain on the std cam and a wet belt drive on the 4-7 swap. The std cam made 344hp at 5700 and 371 ft/lbs, the 4-7 swap cam made 372 hp at 5900 and the same torque. The 4-7 swap cam seems to hold its torque much better then the std even though the intake and heads are the same, I can see the belt drive freeing up 5 hp or so from this one test I am seeing 23 hp gain from the swap.

I think I am going to go with the 4-7 cam on my motor and add roller cam bearings just for the heck of it, a wet belt system would be a nice touch but for the raised cam block an extra 800 bills is not in the budget!..

 

Just curious.... Does that 4-7 swap change the sound in any way?

 

Not that I can tell on the dyno, in a car on the road or side by side another car it may. When we get these in their cars we will know for sure.