??? 700 cylinder mods for turbo sled

[BlowinSmoke]

Wanted to hear what cylinder and head mods people have made on the CFI 700 series engine. This means if you have made modifications and have facts or proof of the out come, I'm interested in knowing.

I'm currently in the process of rebuilding my (08) CFI 700 turbo engine and considering machining the cylinders down to inprove the lower and mid range throttle response. I understand that with good clutching this is also accomplished but interests in engine mods as well.

Please don't make this thread into a B.S. fest of unrealistic opinions!!!

Thanks Erik

 

[tree climber]

i put on low compression head... i dont know why you would want to increase the compression?

 

[slash]

which 700 ?

 

[BlowinSmoke]

I'm working with the CFI 700 series motor. My motor already has an aftermarket head from Brad at Power Addiction.

 

[Ryanlilly]

Anyone know if someone makes a low compression head for liberty 700?

Sorry not trying to hijack your thread.

 

[mountainhorse]

FTX makes one.

Lower comp heads are great for more boost...

Everything has a tradeoff though... the bottom end torque with a low comp head is not as good as a stocker... but the stocker does not have the same top end potential.

Dome shape also plays a large roll.

 

[tree climber]

i may be wrong but i think the one from ftx is just one of brads... when i called brad for my head he was out and had me call kurt to get one

 

[mountainhorse]

You are correct... Brad and Curt are working together.

 

[FTXMOTORSPORTS]

Ryanlilly, don't know if you noticed, but we are just down the road from ya in Puyallup!

We can also machine a performance combustion chamber in any compression ratio you want into your stock head as a less expensive option

and if anyone is looking for bottom end torque....you oughta call and chat with us sometime.

Curt

 

[Ryanlilly]

Ryanlilly, don't know if you noticed, but we are just down the road from ya in Puyallup!

We can also machine a performance combustion chamber in any compression ratio you want into your stock head as a less expensive option

and if anyone is looking for bottom end torque....you oughta call and chat with us sometime.

Curt

Ill be down friday to talk to you!

 

[Spaarky]

Everything has a tradeoff though... the bottom end torque with a low comp head is not as good as a stocker... but the stocker does not have the same top end potential.

Eric.. please explain your theory further. I would agree, a low comp will loose bottome end.. but why would the stocker loose on the top?

I have my own theories and applications.. just curious what point of view you are coming from.

and if anyone is looking for bottom end torque....you oughta call and chat with us sometime.

If that statement doesnt make the phone ring off the hook, I dont know what will. Everyone wants more bottom end, even my 3 year old on her 120. I will be calling sometime this summer..

 

[BlowinSmoke]

Well the thread went to hell in a hurry. Apparently some of us can't follow who is speaking about what or quoting who!

I'm Erik and was the one who started this thread with intensions of finding out who has made successful mods to their 700cc efi engines backed with a turbo system.

To make myself clear! I already have a low comp turbo head cut by Power Addiction (Brad). My plan is to take 24 thousands off the bottom of the cylinders and raise the exhaust port back up. This should make more crankcase pressure and force the cylinder full of air/fuel sooner. Hopefully this will help in the Low and Mid range for great Boon Docking but at the same time have great top end on the boost.

You can't knock it until you've tried it or seen it done. I would like to hear from those whom have spent the time doing the R&D work not tire kicking theory pushers.

Thanks Erik

 

[Spaarky]

Well, the one of the foremost in 700cfi/turbo engine mods answered the thread.. but didnt spell it all out. i wouldnt expect him too, thats what they get paid for. Pick up your phone and call Curt...

 

[mountainhorse]

Eric.. please explain your theory further. I would agree, a low comp will loose bottome end.. but why would the stocker loose on the top?

I have my own theories and applications.. just curious what point of view you are coming from.



If that statement doesnt make the phone ring off the hook, I dont know what will. Everyone wants more bottom end, even my 3 year old on her 120. I will be calling sometime this summer..

With the same octane... you will be able to push the boost level on a lower comp head more than you will a stock (higher comp head for NA use). It May be possible to match the same boost and output as the low comp head but you will need to add octane.

Now there are some people on here that will argue special situations or special dome shapes or some other change... I'm referring ONLY to the change in static compression ratio... not splitting hairs.

 

[mountainhorse]

My plan is to take 24 thousands off the bottom of the cylinders and raise the exhaust port back up. This should make more crankcase pressure and force the cylinder full of air/fuel sooner.

Erik,

Won't this DROP the exhaust port...open the transfers later close them later as same with the exhaust port... actually shortening the open-port duration??
Also, is there adequate cylinder-skirt to Crank wheel clearance for this modification?

 

[Spaarky]

MH.. thoughts that what you were getting at, just wanted to make sure. I am in the "special situations" category...

 

[Eli]

Unless Brad opened up the squish an extra .024"on your head, you are going to be way off in that department.

 

[tree climber]

just add nitrous to spool that pig up faster....

 

[FTXMOTORSPORTS]

What Erik is trying will work, and will help him augment the n/a bottom end torque of the cfi 7.

He will port the main exhaust back up after "dropping" the cylinder. He will also re-cut the chamber to compensate for the lower overall cylinder height to correct the c/r and squish.

Erik, you are starting on the right path and you will be pleased with the results although there will be much more to be had if you understand and can carry out the finer points of porting and port volume/shaping...thats all I'm gonna say!

 

[Eli]

The "fix kit" for the 800 has a piston that is approximately .010" taller, effectively lowering port height. With the combined slight compression increase, people are noticing improvements. I am interested to see how this works out in the long run.

Will transfers need to be raised?


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