highest compression and still on pump gas?

[fiveoho]

lol @ Mike

11:1 is about as high as I will usually go for an alum head street motor, even when you take all items in consideration it can be borderline. With some hot air temps or really cool good air you have to be careful that you do not detonate, timing is crucial. You can get into Dynamic compression, bleedig cylinder pressures off,etc to help explain it all but that is over most guys heads...

Depending on your pistons, heads you may only be able to acheive 10.x:1 compression or lower. What are the specs on the parts you are using. I have a very good comp calculator....

306
new stock block
new stock rods
new stock crank
afr 185s (spring/valve upgrade)
tfs stage 2 cam
tfs street heat intake
forged pistons (unsure of specs)
bbk 70mm tb
pro-m 75mm ma
24# injectors
190 pump
aeromotive fpr
mac shorties / free flowing exhaust
3.90 gear


i know cutting those pistons to allow for that cam will drop my comp some. along with a thick gasket and the alum heads.

tell me this- judging from my parts, how high can i go on my compression and still be SAFE to use pump gas. also , if i make say 10.5:1 and if i make 9.5:1.....how much power difference would be between the two? would power suffer?

thanks. really appreciate all the help

 

[Rick 91GT]

Do you have any idea on the PT# for the pistons? Or the size of the valve reliefs, I can't crunch any numbers with out it.

 

[fiveoho]

bud i sure dont.

not sure when i can find out. if i can, i will let u know.

can it still make good power if it was to turn out around 9.5:1?

 

[vikingpower]

Read up on the Engine Masters series that PHR does, those guys pull out all the tricks to run on pump gas. I think the last winner in the big block shootout ran 11.5:1 C/R. But they have to use 91 octane.

 

[Rick 91GT]

bud i sure dont.

not sure when i can find out. if i can, i will let u know.

can it still make good power if it was to turn out around 9.5:1?

Sure my old 302 combo only had 8.8:1 after notching the pistons, made 340RWHP and went 11.7's @ 116.

 

[Rick 91GT]

Read up on the Engine Masters series that PHR does, those guys pull out all the tricks to run on pump gas. I think the last winner in the big block shootout ran 11.5:1 C/R. But they have to use 91 octane.

I agree however that can get expensive...

 

[fiveoho]

Sure my old 302 combo only had 8.8:1 after notching the pistons, made 340RWHP and went 11.7's @ 116.

340rwhp???????????????????

how the crap did you do that? im in no way doubting you, im just impressed. was it NA? can you see me making 285 - 310 rwhp with my combo with lower compression?

 

[Rick 91GT]

SHORT BLOCK
-89 Block
-89 Stock crank, rods and piston (notched for clearance)
-AFM N-61 Cam
-FMS Steel Timing Chain
-Canton 7qt T-Style oil pan and pick-up
-Melling Standard Volume Oil Pump
-ARP Pump Shaft

TOP HALF
HOLLEY SYSTEMAX II KIT
-Holley Avenger Series Heads PT#300-575 2.02" x 1.60" valves port matched to 1262 gasket
-Holley SysteMAX II upper ported to 80mm
-Holley SysteMAX II lower port mathed to a 1262 gasket
-1" Phenolic Spacer
-75mm Accufab TB
-80mm EGR DELETE Plate (custom)
-76MM C&L KIT
-Fabbed Alum Valve covers with Stef's breather tank

COOLING SYSTEM
-Ron Davis Racing Radiator
-Stewart High Flow Water Pump
-180 Degree Thermo
-16" Perma Cool Electric Fan

FUEL SYSTEM
-Walbro 255lph HIGH PRESSURE pump
-30# Injectors
-Stock rails and lines
-Paxton AFR

EXHAUST
-1-5/8" Ceramic coated Mac long tubes
-2-1/2" MAC Flowpath Off Road H-Pipe
-2-1/2" MAC Flowpath Cat Back DUMPED

SUSPENSION
-70/30 Lakewood Struts
-50/50 Lakewood Shocks
-Eibach Drag launch kit
-Steeda Chrome-Moly Sub frames
-SSM lower GONE 11/1/2002
-Metco Aluminum lowers, anti squat plate not installed, Delrin bushings
-Stock Boxed Uppers GONE 11/1/2002
-JD's Performance Double Adjustable Uppers
-RNH PERFORMANCE Stainless Steel torque box re-enforcement kit (e-mail me for details [email protected])
-JDM Caster/Camber Plates
-S&W 8pt FULL CUSTOM with X brace.

DRIVE TRAIN
-3:73 FMS gears
(SOON TO BE 4:30)
-STOCK AXLES! (SOON TO BE STRANGE SPOOL 33 SPLINE AXLES, C-CLIP ELIMINATORS)
-FMS Aluminum Drive Shaft
- Energy Suspension Tranny Mount and Frame Bushings
-Lakewood SFI Bell housing
-SPEC Stage III Clutch
-UPR triple hook Quadrant and Cable
-ROMAC SFI Balancer
-Mid South Eliminator Alum. Wing

ELECTRONICS
-MSD 6A
-MSD Blaster 3 Coil
-MSD Billet Dist.
-LIVE WIRES
-SPEEDBRAIN ECU
-Power Master 140amp Chrome Alternator

www.rnhperformance.net

 

[fiveoho]

VERY impressive

lengthy, expensive list you have. but it all works well together tho

can you see me making 285 - 310 rwhp with my combo with 9.5:1 - 10.
0:1 compression?


thanks again for your help

 

[fiveoho]

?

 

[Grn92LX]

Yes you should dyno over 300hp. But it doesn't matter what we say, if you really want to know get the car running and throw it on a dyno to tune it. That street heat manifold will be a restriction. I had it on my old 302 with a smaller cylinder head and it was a restriction. Your engine combo would like an rpm manifold with a ported lower

 

[fiveoho]

Yes you should dyno over 300hp. But it doesn't matter what we say, if you really want to know get the car running and throw it on a dyno to tune it. That street heat manifold will be a restriction. I had it on my old 302 with a smaller cylinder head and it was a restriction. Your engine combo would like an rpm manifold with a ported lower

ur prob right. i sorta got a deal on the intake and at the time, i was under the impression that it makes good bottom end power ( i hope it does ). i guess i can go ahead and plan a future upgrade of a better intake.

i appreciate the confidence on the 300 mark....i hope u are right. like u said, i just need to get it together and see what she'll do.

thanks again

 

[Grn92LX]

You can always swap to a track heat upper. Its a direct fit/swap.

 

[fiveoho]

true. is the lower the same on the street and the track?

 

[Grn92LX]

Yep. Hence why its a direct fit/swap.

 

[fiveoho]

 

[5spd GT]

Also, what accessories are you running? I'm assuming all of them. If you delete your powersteering or a/c (both)...that will gain you some more power as well...but I figure if you want to daily drive the car I wouldn't...

Yep, the Street Heat will have good bottomend...

 

[fiveoho]

yea i def want to keep my power steering and AC. im sure that would free up a few ponies tho. even tho its a weekend car, i still want the accessories.