Its a 91 GTA with following mods, any help and tips to tune this set up are greatly apreciated. Intake and exhaust need to be stock for the moment, for inspection.

EBL will be running it with high octan fuel. Should be ready tu run the following week.

Short block:
- L98 Arp Studed 2 bolts mains
- eagle specialties cast 3.75 crank
- eagle I beam forged Rods with ARP Bolts
- Flat Top speed Pro piston (+5 cc)
- Fel Pro 1003 gasket head (0.041 inch compressed height, 9.1 cc compressed volume)
- AFR 195 Eliminator heads with 65 cc combustion chamber
- stock ratio (1.5) stock form lunati rockers
- camshaft: hydraulic roller, XR 282HR from comp cams; duration @ 0.050 inch 230 and 236, duration seat to seat 282 and 288, valve lift with standard rockers 0.510 and 0.520, lobe centerline 110, intake centerline 106.
- stock TPI for now, later Holley Stealth Ram with 58mm throttle body and 30 lbs injectors
- Stock exhaust for now, later Hooker super competition long tube, 1 3/4 primary
- PATC stage III raptor Th700 Tranny with 2400 stall.

According to Eagle specialties engine dimension calculator

deck clearance : 0.025 inch ---> head to piston clearance 0.066 inch-->> a bit too much
compressio ration: 11.63:1 ---> a bit too much too

 

that is sounding almost like the same engine I'm building right now exept for the lingfelter supper ram package that I'm putting on top and the 1.6 rockers that I'm installing I'd love to see what you get as numbers once your done

 

probably are going to have to change the pistons out for dished pistons. holy crap man. lol. your going to blow the heads right off that thing.

 

 

I'm not seeing the compression ratio has high as you listed. It seems to be around the 10.3:1 area. I used the KB calculator (http://www.kb-silvolite.com/calc.php?action=comp) and then another at http://www.rbracing-rsr.com/compstaticcalc.html

With the cam and AFR heads it won't be an issue.

RBob.

 

Thanks for the heads up and helping clarify the issue, yes the block has been bored 0.030 over.
CR was calculate wrong using doomed piston value on Eagle specialitys site. (Pistons: Speed Pro ZH860CP, Compression Distance 1.425in, Piston Head Volume +5cc).
Around 10.3:1 sounds good, to me, though I have no experience.

To clarify this is a friends project, it is great to participate and I'm looking forward to start tunin it.
He is having a little delay due to the AFR 4 center intake manifol bolt bores not lining up correctly with the stock intake manifold.

 

I have a similar setup running 12; 1 no problems. A head with a effective chamber design like a AFR or TFS will do that easy

 

.025 deck and .041 gasket give .066 quench; not good.
A big quench on a hi comp motor will more likely detonate than a lower quench with higher compression.With a big quench the mixture is not sqeezed in from the sides of the bore leaving pockets of fuel that can ignite on their own ( detonation )
If you are not cutting the block down further I would be looking at a thiner gasket to get better quench figure
0.040 quench is the prefered number

Dynamic Compression Ratio (DCR) is more important than static CR .The longer the duration of a cam, the less the effective CR becomes ; because the piston is further up the bore before the valve closes; effectively a shorter stroke and lower actual CR (DCR).

Good calculator here to download and work out DCR using cam specs
http://members.uia.net/pkelley2/DynamicCR.html
http://www.popularhotrodding.com/eng...eze/index.html
https://www.thirdgen.org/forums/powe...ce-vs-dcr.html

 

Just run the numbers for
As you spec above
10.3 static CR / 8.2 DCR with bad .066 quench

With a .015 gasket to give good .040 quench
Static CR 11:1 / DCR 8.6
DCR of 8.6 easy doable with good head design and quality fuel
FWIW
I am running 12:1 CR ,0.041 quench ,DCR of 8.7 on 95RON fuel with no knock counts

 

Thanks a lot vetteoz, thats some great new needed information.

 

11.1 should be No prob at all with a street car..

remember Alum Heads and FUEL injection make life good.... (spelling)Beer

 

I ran 11 to 1 with my 383 on 93 octane just fine. I even ran it lean as hell and up to 39 degrees timing once during intial tuning phase, and never had knock counts. AFR heads have great chambers and do well with compression as long as the cam is decent sized and that cam should be ok in that motor.

Do think zero deck block would be a nice idea for better quench height.

As far as tuning goes, just get the tuning software/burner/chips from moates.net and go at it. read the forums here and learn. MAP systems i feel are abit more tricky to tune than MAF. Atleast in my experience so far i had a good MAF tune in matter of few weeks and its been several weeks already with my MAP system and i'm still no where near done

Problem is TPI/Stock exhaust on that motor will seriously handicap that build and require a much different tune to run than when you swap to HSR/exhaust

 

hey 76 i have a set of SLP with out smog

SS headers 1 3/4 tubes and Y set up to run into a edlebk Cat Back.


cheap.. hate to just toss them.. but im also going to Hooker 2210's.
ran 12:00's with this set up.. my cam is 586 lift mech roller.
they worked good.. but the fogger NOS needed's a Bit more tube
only made it into the low 10's 1 time..open header.

the headers only have 10.000 miles on them if that.. new back in 93.

 

I hope EBL flash will do the trick. I wish I could use MAF but dont think EBL can use it.


We have no choice, has to be inspected first, no fun if it cant be driven. The longtubes and HSR are collecting dust for the moment.