Scat SJ Procomp I beam

[KnightEngines]

Does anyone know if the scat SJ Procomp I beam is a dedicated SJ forging or just a LJ forging with a smaller hole?

On their site the SJ & LJ versions are listed at the same weight, you'd think if the SJ forging was the same as LJ then it'd weigh more, so chances are it is a dedicated SJ forging but I'd like to be sure.

Any problems with running these rods at 7200rpm max/580hp/3.58" stroke (light 1.1" comp height piston) in an edurance racing engine - will do most of it's work between 4500-6500rpm, but will occasionally see 7000+.

[steve cowan]

hi tony,

i cant answer your question on the manufacturing process,sorry
i recently bought a set of i-beams 2-icr6000-7/16
big end 426 gr
small end 160 gr
7/16 x 1.400'' 8740 arp bolt, 64 ft/lb torque 0.0046'' stretch (do not exceed)

i think they are a nice budget rod,they measured up well and i spent a fair bit of time on measuring and doing a rod bolt stretch,measure cycle so the are ready to go
i found at 64 ft/lbs initially they only came up to 0.003'' stretch
after a couple cycles they all were consistant at 0.004'' stretch at 65-70 ft/lbs torque
measured up with a set of king bearings and i am using the cast 9000 3.75'' crank
i have a spare early 010 block that i am building a 10.1:1 nitrous engine going to make 580-600
david vizard has posted here making 600hp from this crank and rod combo multiple times so i am confident
i would really like to hear your results on that combo you are doing,i would say that might be up and running a bit sooner than mine

steve cowan

[mag2555]

Well one comment I can make is that a perfere I beam rods to H beam, as the pockets formed by the sides of the H beam can keep a lot more oil and hence windage going on in a crank case and cost you power!

[racear2865]

Well one comment I can make is that a perfere I beam rods to H beam, as the pockets formed by the sides of the H beam can keep a lot more oil and hence windage going on in a crank case and cost you power!

Ok, you got my curiosity up, how did you confirm that the pockets hold more oil. The I-beam has a trough in the front and rear versus pockets in the side. Just asking, not condemning.
reed

[mag2555]

15 years ago with a dyno test where the only difference was H beam or I beam rods as the oil level that remained in the pan @ 7000 rpm was kept track of.

[Warp Speed]

Well one comment I can make is that a perfere I beam rods to H beam, as the pockets formed by the sides of the H beam can keep a lot more oil and hence windage going on in a crank case and cost you power!

Huh?!?

[wyrmrider]

you might want to consider choice change depending on size of crankpin
take a look at each on a Chrysler Hemi crank vs a Honda

[KnightEngines]

i would really like to hear your results on that combo you are doing,i would say that might be up and running a bit sooner than mine

It's a mate's hillclimb/circuit engine, early head holden.
We had it apart for a freshen (I built it in 2010) & some pretty serious upgrades - found a crack in the old CSR Honda journal crank so we're going with a COME steel billet offset ground from LJ to SJ & 3.58" stroke to keep the capacity at just under 6L & stay legal for CAMS racing classes.
It was previously making about 490hp on pump fuel with a 248/252 SFT cam, TP dual plane intake, 750 carb & wet sump.
I've reworked the heads to get flow up from high 240's to 260+cfm & from 2" MCSA to 2.2" MCSA at the pinch (yes, HQ castings & yes, they are rather large!), we've switched to a custom grind crane SR cam - 262/266 on 108, .710/.670" lift.
Bumped compression to 12.8:1 & will run on E85.
We've also got a peterson 4 stage dry sump with ASR pan for it & will be running a lower tension ring pack & pulling around 8" of vac with the dry sump.

Plan is to hit 550+hp with a HQ head holden & reclaim a few lap records - he's .03 seconds off the pace at collingrove & a bit more than that at Mt alma, still has the record at one tree hill & ballarat, but the gap is closing.
Another 60-70hp & 20-30ft/lbs will fix that.

[steve cowan]

damn tony that is bad ass
very tough numbers from a red 308 early casting head
i cant remember,did you fit a 2.02'' or a 2.05'' valve?
when you open the pinch do you bias the port to suit or is just open the port walls and roof evenly through the runner
does the valve bowl increase or do you lay the short turn back further?
to achieve near 13.1 comp are the heads rolled over a heap?i suspect the chamber must be around 50cc
hope you dont mind the questions,i have not heard of many guys making good power like that very impressive
i know i always ask alot but would like to see a photo or two if possible
thanks for sharing

steve c

[KnightEngines]

Nah, heads not rolled over, just flat milled, chambers are 50cc.
Porting the old HQs to this level you don't get much choice where you put the port - there is only so much metal to the water jacket, it's pretty much a case of just making them as big as you can fit in the casting & getting the short turn right. Both walls, the roof & the bowls are pretty much maxxed out. Valves are 2.02 & 1.625".
I'll pop some pics up over the next couple of weeks, I'll have the new crank this week, the heads & intake are done, dry sump is mostly done & pretty much all of the parts are here, should be on the dyno before the end of September.