Strictly Drag Only high compression Stroker Build Questions

[KenoshaComanche]

So just a little insight, i have a 1988 jeep Comanche with a 4.0 in it that was used in an NHRA stock class racing so basically everything is pretty much stock spec. since the truck is not running nhra anymore we are making a few changes. im in the process of putting together a bullet proof short block and had some questions.

basics of the build are,
4.6 high compression stroker, forged rods and pistons.
scat 9000 series crank (4cwt)
11.5-13:1 compression ratio.. we haven't decided how high to go yet
major port match, porting, polishing, bowl blending.
custom made billet roller cam, with retro-fit Solid Roller Lifters
double roller timing set.
running 110 leaded race fuel
we typically run 3800-6800 rpm on our stock rotating assembly 4.0
turning 13.30's at 99 mph in the 1/4
we also run a stand alone accel efi gen6 calmap ecu

1. do i have to worry about the 4.0 "hollow" main caps with the new stroker build? it would be nothing for me to cnc mill up and wire edm new stronger main caps if
there would be no issues with that. itll need a line bore/hone but will it being too strong hurt anything? ill be using arp main studs

2. how high of a compression ratio could i go with the 110 octane fuel? with the high compression do i need arp head bolts have any other worries associated with the higher compression?

3.would it be stronger to go with scat 6.125 4340 i beam rods with icon pistons. or 6.150 eagle h- beam with custom pistons?

4.who is everyone getting there roller cams through? i called up lsm systems engineering. and they had cores in stock but if someone has had a good experience with another company id be happy to switch.

[jeepxj3]

Cool project.

1-Yes do the billet main caps. In fact do a few extra as there might be some buyers, I'd take a set.
2-With your rpm goal and high CR, use ARP head stud kit, not bolts. Also use Victor Reinz or Cometic MLS head gasket. You could probably go about 12.5:1 even up to 13.5:1 as the supercharger guys run 8 pounds boost which like effective CR of 13.9:1. Maybe whatever compression a flat top piston would give you. 0.000" deck and 0.043" head gasket and flat top 0.030" over pistons would give you 12.43:1 CR, 0.060" would give 12.61:1.
3-Eagle H-beams are unavailable, maybe a rare used set somewhere. Use Scat forged with ARP bolts and get custom forged pistons, skip the icon's.
4-roller cams? not really available. 505 has one, heard poor reliability. No roller lifters available, hard to keep from turning in the block.

-Add Harland Sharp roller rocker arms, adjustable ones if using solid lifters, and good CM pushrods.
-And ported big valve head. Contact Russ Pottenger. He's the best, most experience, can do alumn or steel head.
-Get a custom camshaft, flat tappet. Might have to convert a set of hydraulic flat lifters to solid, if you can mill a set of billet main caps, shouldn't be too hard of a project for you.

Looking forward to what you do. 262CID and ?1.3-1.4hp/cid, 340-365HP.
Or reduce the CR and RPM, 10.0:1 and 6000rpm, and add a bunch of Nitrous!

[Russ Pottenger]

I just finished doing a Stroker similar to what you're looking to do.
The engine is going into a KOH Jeep, therefore reliability and staying within a reasonable budget was the biggest factors in the build.

I think a similar build/recipe might work for you and fulfill your objectives without killing the bank.

It starts with a fully machined blueprinted block. Scat crankshaft, Scat steel I beam rods bushed for Chevy .927 pins. My custom 3.965 bore FT Pistons. The Stroker has one of my fully ported 7120 heads with a finished combustion chamber measuring 62cc. With the piston .008 out of the deck and a .043 gasket that puts it over 12.1
I'm using one of my nitrided custom solid flat tappet Cams with 1.65 roller rockers.

Feel free to contact me if I can help you in anyway.

Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Work (626) 967-1000
Fax (626) 967-7836
Cell (626) 673-2203
Email/PayPal: [email protected]

[jeepxj3]

Hey Russ,
Any more info on that 'stroker that is going to be supercharged' on your facebook page from about 2 months ago?
Is it running? How much boost? power?

I want.

[KenoshaComanche]

So to clarify a few things. I was running a lunati cast flat tappet cam with crower solid lifters and yella Terra 1.6 roller rockers. And Smith bros. Pushrods. My goal is to make a bullet proof short block so I don't have to worry about leaving parts at the track.

We don't want to run any power adders also. Lsm is fully capable of doing pretty much anything I would need as far as a cam or lifters. But at a cost $$$. They quoted me $1000-1400 to retro fit roller lifters into the 4.0 block. Not happening. But as far as the cam, unless someone else makes one other than 505 I'll get it through lsm

I don't want to run head studs because I can't remove the head with out pulling the motor then.. I'd rather sacrifice compression ratio than the inconvenience of the head studs.. Arp Head bolts should be sufficient just not ideal. I'll be using a cosmetic MLS.

The only worry I have about making extra sets of billet main caps is for one were not making a billet cap for the last cap that houses the crank seal. Just don't feel like going through the extra bs. Involved unless it's absolutely necessary. And issue 2, the caps sit in the block with like a .0005-.001" almost interference fit for perfect alignment and any diffence between my block and someone else's would be a problem

[KenoshaComanche]

Here is what it's going in

[jeepxj3]

Way cool, where are you located?

[KenoshaComanche]

Kenosha Wisconsin

[KenoshaComanche]

So I'm curious, why skip the icons? Are there known issues with them or is it just easier to get a Custom set made with more options to personalize like dish/flat top, valve reliefs, ring pack. Etc.

And I just remembered my other question. What kinda valve clearance issues am I gonna run into? Is there a known margin I need to stay within? Like .500" max lift with a .048" quench? Or something to that affect? I'm lost on figuring out valve clearance.

[Russ Pottenger]

So I'm curious, why skip the icons? Are there known issues with them or is it just easier to get a Custom set made with more options to personalize like dish/flat top, valve reliefs, ring pack. Etc.

And I just remembered my other question. What kinda valve clearance issues am I gonna run into? Is there a known margin I need to stay within? Like .500" max lift with a .048" quench? Or something to that affect? I'm lost on figuring out valve clearance.

There so many custom features I could put into my piston at virtually the same cost as an icon. The two most obvious is pressfit pins, and a 5/64 ring, ... and it's ridiculous to have to cut .050 off the deck of the block just to achieve quench.

I agree with you on the head studs. Obviously at 12.1 you're going to need to run race gas, but that's not that much compression to require a head stud. New 1/2 OEM bolts will be fine. The only time I find it's necessary to run the ARP bolts is when I run them on the aluminum Edelbrock, and that so I can run the washers so the bolts don't dig in the bolt seat.

I don't see you ever having a piston to valve clearance issue.
As for quench, .048 is way too much on a race engine. It shouldn't be more than .035

Don't hesitate to contact me if you need help with a piston.

[KenoshaComanche]

I'll shoot you a pm Russ.

Okay so I'm no pro engine builder or anything I'm only 22. I just research ALOT of this stuff. So you said for a race engine quench shouldn't be more than .035"? So if I'm understanding quench right. My deck hieght is .006" and my gasket is .043 compressed. So would that give me a .049" quench On the stock 4.0 I have in now? (We have 2 motors we swap in and out between rebuilds). I've only seen gaskets down to .040" so I would need a positive deck hieght like yours to achieve proper quench?

Press fit pins? I always thought full floating was better?

[Russ Pottenger]

At 22 you're off to a great start and should be very proud.

You're correct you do want to full floating pin. The icon piston only comes with a .931 stock pin diameter, press fit, and stock ring package. What you want is a .927 or .912 pin and bushed rods.

I'd recommend decking the block leaving the piston .008 out and use a .043 head gasket.

Hope this helps,
Russ

[vashxj]

your going to have to do a lot of head work to try to get anything better n/a. the ports just don't flow good. bump that compressing down a little and put a mid size turbo and meth on it

[SIXPAK]

My high comp stroker runs 11.17 with a stock valve ported head. Cam was under .500 lift at the cj5 was 2550lbs

[KenoshaComanche]

Thats the thing. anybody can turbo, supercharge, spray, or v8 swap a jeep if you throw enough money at it. what is really unique is making big (big enough) power with a refined N/A set up. Ill be sending the head to Russ to get worked pretty good.