Detuning 380hp create engine.

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273

273

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Thinking of going with comps xr265hr-14
cause I want more of a daily driver. Plus add rpm airgap. The engine only has 5000 miles on it so I'm guessing reusing stock roller lifters should be fine. But are the stock 380hp create engine valve springs gonna work with this cam ??
Screenshot_20171017-091647.png
 
just a note- comp uses 1.5 rocker ratio, so be sure to recalculate at 1.6 for your magnum heads.
 
What cam is in those 380 horse engines? Are they real radical? (obvously or you wouldn't want to de-tune) Fill us in on why.
 
The 380 hp roller cam specs were 501/513 lift & 288/292 duration i believe.
Consider a swap to just rhoads lifters with current cam perhaps. They will tame your cam on the bottom end.
Just a thought.
Rhoads Lifters
 
Oldschoolcuda said:
The 380 hp roller cam specs were 501/513 lift & 288/292 duration i believe.
Consider a swap to just rhoads lifters with current cam perhaps. They will tame your cam on the bottom end.
Just a thought.
Rhoads Lifters
Click to expand...
They have them in roller for Magnum"s that's cool. That cam is way too heavy on the duration side to be much fun on the street without a big gear and converter. Building for maximum horsepower isn't always the most street-able.
 
I thought of the Rhoads lifters but the ones that take 15-20 degrees of duraration needs adjustable rockers plus the lifters which is double of the cost of the cam it self.
And still be on 108° centers instead of the new cams 114°. They both have similar lift and is only 14° smaller intake duration at 0.050".

The cam that's in it is actually fairly streetable for the size even with the weak 2.96 gears that came with it. Was gonna swap in 3.91-4.10 but remembered what I wanted when was looking to buy a car this summer was a fun daily driver. Not a week end machine.

Gonna save the cam and intake for another project.

Any idea if the stock spring will work with the new cam ?
 
273 said:
I thought of the Rhoads lifters but the ones that take 15-20 degrees of duraration needs adjustable rockers plus the lifters which is double of the cost of the cam it self.
And still be on 108° centers instead of the new cams 114°. They both have similar lift and is only 14° smaller intake duration at 0.050".

The cam that's in it is actually fairly streetable for the size even with the weak 2.96 gears that came with it. Was gonna swap in 3.91-4.10 but remembered what I wanted when was looking to buy a car this summer was a fun daily driver. Not a week end machine.

Gonna save the cam and intake for another project.

Any idea if the stock spring will work with the new cam ?
Click to expand...
Sure seems they would but can't say for sure. You should also check your DCR before pulling the trigger on the cam.
 
Is that a “Magnum” cam? Short snout?
 
I would go smaller to the 262-hr-12, it will give you alot of torque to over come those gears, and it has the long snout.
 
It's probably long snout cause it does have the LA timing cover and mechanical fuel pump.

Switching to Holley sniper so don't need the mechanical pump. Will the comp magnum cam work behind the LA timing cover ?

DCR should be fine it's only 9:1 CR.

I'm gonna stick with the 2.96 for now and see I do have short 26" tires on the back.
Probably in grade to 3.23 or 3.55 later.

Anybody know about the valve springs if they will work with the comp cam ??
They both have about the same lift but the newer cam will have shorter duration so faster ramps.
 
Take a look at the Comp 264HR-12. We've used this in several Magnum 360's. A little less duration than the one you are looking at and a little more lift. Works great with highway gears and mild converters. Pushed one Duster with 3.23's and worn out 30" tall slicks to 13.8 in the quarter. Will sit in traffic all day too.
 
380 cam is 230/236 @ .050 .....on a 108 LSA....

the cam has a long snout...at least the ones i have
 
Ye
273 said:
It's probably long snout cause it does have the LA timing cover and mechanical fuel pump.

Switching to Holley sniper so don't need the mechanical pump. Will the comp magnum cam work behind the LA timing cover ?

DCR should be fine it's only 9:1 CR.

I'm gonna stick with the 2.96 for now and see I do have short 26" tires on the back.
Probably in grade to 3.23 or 3.55 later.

Anybody know about the valve springs if they will work with the comp cam ??
They both have about the same lift but the newer cam will have shorter duration so faster ramps.[/QUOTE

Yes the ong snout is for a la timing cover
Click to expand...
 
Springs you have are fine.
The wide LSA on those cams are to keep the PCM happy on FI motors. A retrofit hyd roller would work if your staying with a carb. A custom grind is around $30 bucks more and worth it IMO.
 
mderoy340 said:
Springs you have are fine.
The wide LSA on those cams are to keep the PCM happy on FI motors. A retrofit hyd roller would work if your staying with a carb. A custom grind is around $30 bucks more and worth it IMO.
Click to expand...


One of the reasons I'm swapping is I'm gonna be running Holley sniper efi.
 
You could add the dual plain intake and advance the cam you have to 102 or 100 and see how it works for you, just a thought. Lots cheaper than screwing in a new cam. Then go over your timing curve, and look at your exhaust to see if there is anything you can do in that department. Check out the chapter on exhaust in HOW TO BUILD HORSEPOWER second edition, by David Vizard
 
gregsdart said:
You could add the dual plain intake and advance the cam you have to 102 or 100 and see how it works for you, just a thought. Lots cheaper than screwing in a new cam. Then go over your timing curve, and look at your exhaust to see if there is anything you can do in that department. Check out the chapter on exhaust in HOW TO BUILD HORSEPOWER second edition, by David Vizard
Click to expand...

Plan on adding airgap, then engine as is ain't really that bad little soft under 2000 rpm which doesn't help I'm running 2.96 gears.

I'm sure advancing the cam would help but I want to regain some fuel mileage.
The stock cam seems to be modeled after thumper type cams. But the new cam will have about half the overlap at 40°.

I plan on checking the back pressure of the exhaust but looks pretty free flowing.
 
273 said:
It's probably long snout cause it does have the LA timing cover and mechanical fuel pump.

Switching to Holley sniper so don't need the mechanical pump. Will the comp magnum cam work behind the LA timing cover ?

DCR should be fine it's only 9:1 CR.

I'm gonna stick with the 2.96 for now and see I do have short 26" tires on the back.
Probably in grade to 3.23 or 3.55 later.

Anybody know about the valve springs if they will work with the comp cam ??
They both have about the same lift but the newer cam will have shorter duration so faster ramps.
Click to expand...
throttle body ? If so, a single plane is better for them. It might kill a few h.p. on the bottom end too. I don`t understand detuning a 380 horse engine tho, u ain`t got much to start with.
 
famous bob said:
throttle body ? If so, a single plane is better for them. It might kill a few h.p. on the bottom end too. I don`t understand detuning a 380 horse engine tho, u ain`t got much to start with.
Click to expand...
Agreement..if calling anyone, send MoparMagnum,..a P.M. ..man. He has done all of this,already. :) Driveable central,done the easy way.
 
famous bob said:
throttle body ? If so, a single plane is better for them. It might kill a few h.p. on the bottom end too. I don`t understand detuning a 380 horse engine tho, u ain`t got much to start with.
Click to expand...

Chrysler call it a 380hp create engine (stock 5.9l longblock) but they dyno more 400-420 hp. It's not the hp I'd rather keep the hp. I plan on porting the heads to make up for the little bit of a lesser cam.

The stock cam is more like a thumper cam.
I want decent mileage plus be a little more civil since it will be a daily driver. The new cam is about 15° smaller @ 0.050" and about the same lift. It's mainly the overlap that will be cut in half from about 80° to 40° cause the LSA going from 108° to 114° for the efi and mileage.

Why stay single plane ?
I know on engine masters they had a problem with dual plane but on the Holley forums says it's not a problem.
 
I plan on taking my 5.9l jeep off the road next year once I get my bronco back on the road and make the jeep a stripped down a drag only car.
It pretty beat.

So I'll be using the cam and intake on that later.
 
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