4.7 Jeep stroker..Dyno Day

[corvette90]

hi all

friend of mine likes offroad driving in his Grand Cherokee and decided to build a stroker...

Motor is Inline 6 with 4.7l, 3.935 bore and 3.875 stroke
camshaft comp cams 262/270 .527/.547 lift XE Cam
Edelbrock jeep aluminium cylinder head
Harland sharp roller rockers
FMS24lbs injectors
tubular headers, very free flowing (loud) exhaust
compression 10.1

the engine in its stock 4.0 form dynoed 170hp, thats about what its rated (177hp)

after all work, the stroker dynoed 233hp@5000 rpm and 280ftlbs (dont know exact rpms by now)

now he is really disappointed, because you find the wildest combos rated at 300 (advertised) hp in the internet from several companies, using the very same parts we did...

pcm was tuned, according to wBo2 and dyno operator close to perfect..

another thing, the valvetrain is near quiet with cold engine, and very loud with hot engine..sounds like a diesel...
rockers dont hit valve covers, clearance everywhere more than enough..also no spark knock of course, the clackering is going in line with rpm and is very constant

i played around with DD2k (yes, i know.....) and i can do what i want, change induction system, exhaust, cam, i cant get over 280hp (DD2k hp)

im open for every input, please respond

thank you

[PackardV8]

Coincidentally, a potential customer was in last week discussing essentially the same build. Must be the flavor of the week on the jeep-o-sphere.

By using an aggressive lobe profile, these cams provide better throttle response and more top-end horsepower than equivalent cams from other manufacturers, while delivering increased engine vacuum.

FWIW, the Comp XE lobes, with an aluminum head, rockers and valve cover often will often be a noisy bastard. Difficult to appreciate how much quieter is the same cam when the head is iron, rockers are steel and cover is steel.

[corvette90]

hi and thank you

ive read that too, that the XE lobes are very loud..

head is aluminium, roller rockers and steel cover...

what concerns me too, how are the internet jeep part suppliers turning out enormous hp?

we have really all the goodies in the engine and have 235hp....

[mag2555]

Well one issue is your running more Exh lift then those springs the head ships with are stated by Edelbrock to handle!

Noise when hot could mean things valve train wise that should not bump into each other are!!
Most springs set ups that Edelbrock sells on non race heads like these suck by the way and I would only run them for braking a motor in at under 4000 rpm.

I would also think that with the E heads increased port size and that Cam that peak hp would be seen at a higher rpm then 5000.

Putting all that aside, 230 hp means each cylinder was using only 148 Intake cfm@28", and with the lift of that Cam and what those heads flow ( 235+ cfm@28") I would say that your Intake Manifold must be a darn big restriction on power!

[Carnut1]

Is this mill using the stock air intake plastics, air cleaner assembly, throttle body and intake manifold? I had a '93 4.0l k&n filter, ported plastics, ported throttle body, custom solid 1" aluminum spacer to enlarge plenum volume, ported intake manifold. Gave it a big enough kick I never installed the ported head I had for it. The issue may be something else as well. Interested in this build a guy at work has a 4.0l he is thinking of stroking. Thanks, Charlie

[jed]

Mag2555 how did you get the 148CFM number from the 230 HP and does it make any difference
If the HP is flywheel ot rwh???
John

[corvette90]

hi to all, thanks for your answers

will try to reply ...

@mag2555 sorry, for the camshaft, made a typo...the cam is COMP Cams Xtreme 4x4 Camshafts 68-239-4, iin fact 262/270, but lift is 493/512...so well under edelbrocks .540

we have checked for clearance everywhere, there is simply nothing that the vlave train can hit....it sounds, the cold oil acts as a damper, and when it thins out, contact is made....even with a cut open valve cover, nothing to see

you are right about max rpm, the Jeep hits the limiter at 5000, i set it higher to 6000 rpm, this gained about 20hp, netted 235 FWHP


@carnut1 intake is the stock intake, the more modern one with the plenum, we also removed every plastic pipe, in fact, we see on the throttle blade during the dyno pulls...so, no restriction here...maybe another thing to look at...the manifold itself is the restriction?? TB is a 62mm unit btw

regards

[peejay]

Try it with a pipe on the throttle body.

Don't discount the idea that the Internet can be full of sh**, too. You made a 30-odd percent improvement, that is nothing to scoff at.

[Carnut1]

The later intake has nice curved runners, old one looks like a six tang fork. New one must be an improvement.

[jeff swisher]

My first 350" to bore larger I went to the local machine shop and left there with a fresh bore /hone and piston to wall clearance of .0015"
Cast Zolner piston.
I installed all the goodies i pulled out of it when it was a worn out stock bore 350.
268H cam and ported 624 heads.. it would rev to 6500rpm and was quite quick.
After the fresh pistons and bore it would only rev to 5000 rpm and power nosed over.. never nosed over with the loose factory pistons until past 6500 when i ran out of valve spring.

I wonder if the engine of yours was set up tight. That is a killer of power.

After that first .0015" deal I went .0045" and my little 350's came alive.. I eventually went to .0035" and no difference in power.
Old USA made cast pistons..Not hypereutectic.

Too much silicone in those Hyper' pistons and I do not care for that.

My pistons had skirts like a factory piston. I suppose if you run those new very short type skirts a tighter piston to bore clearance would not hurt as much.
I do not know though..I have not ran the short skirt deals yet.
But like i said above you can be down on Power and RPM as much as 1000 rpm.

Remember the performer RPM cam/ heads/ intake for the 350 when they advertised all that HP and TQ it made.
I researched that build and it had .0065" piston to wall clearance.. Forged pistons of course.
Things to think about.

[Truckedup]

The later intake has nice curved runners, old one looks like a six tang fork. New one must be an improvement.

Not necessarily better...

[Carnut1]

The later intake has nice curved runners, old one looks like a six tang fork. New one must be an improvement.

Not necessarily better...

I haven't tried either on the bench. I would think the design change would offer an advantage in performance since it looks like a more difficult or expensive piece to cast.

[peejay]

That doesn't mean that it might make more ultimate power, it just means that it was able to fill a specific OEM-level need.

I would think that a gigantic throttle body like that would be better suited to a smaller plenum. 62mm is huge even for 300hp.

[user-17438]

hi all

friend of mine likes offroad driving in his Grand Cherokee and decided to build a stroker...

Motor is Inline 6 with 4.7l, 3.935 bore and 3.875 stroke
camshaft comp cams 262/270 .527/.547 lift XE Cam
Edelbrock jeep aluminium cylinder head
Harland sharp roller rockers
FMS24lbs injectors
tubular headers, very free flowing (loud) exhaust
compression 10.1

the engine in its stock 4.0 form dynoed 170hp, thats about what its rated (177hp)

after all work, the stroker dynoed 233hp@5000 rpm and 280ftlbs (dont know exact rpms by now)

now he is really disappointed, because you find the wildest combos rated at 300 (advertised) hp in the internet from several companies, using the very same parts we did...

pcm was tuned, according to wBo2 and dyno operator close to perfect..

another thing, the valvetrain is near quiet with cold engine, and very loud with hot engine..sounds like a diesel...
rockers dont hit valve covers, clearance everywhere more than enough..also no spark knock of course, the clackering is going in line with rpm and is very constant

i played around with DD2k (yes, i know.....) and i can do what i want, change induction system, exhaust, cam, i cant get over 280hp (DD2k hp)

im open for every input, please respond

thank you

That's why I don't play the numbers game. If a customer wants 1000hp they get 1000hp. Not internet hp. I see so many time peoplefollow a build or buy an engine from a big name, then it won't run the number or mph it should. Stick it on the dyno and show them it's 80 to 120 hp off from the sheet they sent or posted on the forum. I have had ex customers send their engines into big name shops in the quest for power heads picked up 50cfm, engine made 120 more hp. Put it in the car, runs the same time and mph. Put it on my dyno, number lay down exactly what it made 2 years ago, never hear from the guy again. My question is why didn't they dyno the engine first or flow the heads first to make a baseline? Because they k ow their numbers are happy. It's to get sales.

I tell people to leave the internet builds where they belong. And we will build you what you need.

As fsr as your build goes, my guess would be intake manifold and cam lift. But that's a stout number. I think the owner should be more than pleased. You increased power by 1/3. That's a big gain.

[corvette90]

"That's why I don't play the numbers game. If a customer wants 1000hp they get 1000hp. Not internet hp. I see so many time peoplefollow a build or buy an engine from a big name, then it won't run the number or mph it should. Stick it on the dyno and show them it's 80 to 120 hp off from the sheet they sent or posted on the forum. I have had ex customers send their engines into big name shops in the quest for power heads picked up 50cfm, engine made 120 more hp. Put it in the car, runs the same time and mph. Put it on my dyno, number lay down exactly what it made 2 years ago, never hear from the guy again. My question is why didn't they dyno the engine first or flow the heads first to make a baseline? Because they k ow their numbers are happy. It's to get sales.

I tell people to leave the internet builds where they belong. And we will build you what you need.

As fsr as your build goes, my guess would be intake manifold and cam lift. But that's a stout number. I think the owner should be more than pleased. You increased power by 1/3. That's a big gain."

thank you for your statement, i also would say for a N/A engine, thats a good amount of power gain..
we will swap the cam anyway, because of the really loud valvetrain..its really loud, louder than a mechanical train...still no sign of contact or collapsed lifters
and look for a different intake, but you dont have a lot of choice here...i dont know how well the intake responds to porting...we´ll see

thanks again