I know they are just numbers but thought these were a little low...maybe not. Car: 70 GS 350 Forged pistons Gessler stage 2 heads, larger valves & springs TA Performance 284-88 cam, .475 Lift 9.5:1 compression Stock intake and exhaust manifolds - 2.5" mandrel bent exhaust 3.42 rear. Rebuilt carb from everyday performance - .72 jets (I think) Only mustered up 249 HP and 282 Torque at the wheels at 5200 RPM. car drives great and I don't have any issues with it, but should I leave well enough alone? Thinking of adding headers from TA Performance. Engine is a factory replacement block and trans is out of a 1978 car, according to the VIN on the trans so I'm not sure originality is an issue. Thoughts?
That’s decent. Figure another 30-50 for drivetrain loss . So 280-300 flywheel Power. There’s probably some tuning left in it.
Factory was 315 - all the power increases should put it at around 350 at the flywheel. Every dyno is different so I'm not all that concerned. But with all the engine mods, I would think headers would open it up quite a bit, since the heads are ported and breathe better. I'm just not sure how much of a pain they at to install without a lift. Decisions. BH
That 315 # was not accurate With 9.5 to 1 comp and iron manifolds you are doing very well A true 350hp 350 is not very common
Back before about 1972 the Gross HP numbers were very optimistic as were the compression ratio's. I had a 1963 HP 215. Supposedly 11 to 1 compression and 200HP. Pistons were probably 10.25 and HP around 180 realistically. The manufacturers would also downgrade high HP numbers for insurance prices and to give a competitive edge against other makes.
Yes, factory ratings were a numbers game. The 10.2 compression was the blueprint only. The actual compression ratio without the factory steel .020 head gasket was about 9.2. So the 315 hp, not achieved. But if your timing is set at factory specs with out a recurve kit , there’s some performance your missing out on. Bump that timing to about 12 initial, with full advance all in by 2800 rpm or alittle sooner depending on what grade of fuel you use.
What rpm did the torque peak at? And what are those numbers? Is that 282ftlbs the peak, or what it had at 5200, or did you mis-type?
Is the intake and exhaust manifolds ported to match the heads? Also curious if the 282 ftlbs is peak?
Being conservative with the dive train loss at 20% that 249 is closer to 300 & the 282 is closer to 388. So I would say NOT BAD for the type of build you have. Headers will wake it up somewhat also. Porting the stock intake would also help. An aluminum manifold, intake, may not add much but will be lighter weight. Just my thoughts.
282 was the peak and it was below the 5200 mark, I forget where the peak torque came at, I'll have to go back and look that up. I believe the exhaust manifolds are ported but I'm not sure about the intake. It's been a while. Thanks for the responses.
Would interesting to see what headers and the TA SP3 single plane intake would do to this. Supposedly you're not supposed to loose low end with that intake and only peaking @ 5,200 RPM with the current setup, even the factory rods can handle to spin more than that.(around another 1,000 RPM with a good balance) The SP3 should definitely raise the peak, the factory dual plane is definitely what is holding the RPM peak back.
Torque was 282.5 @ 4260 Power was 249.33 @ 5030 I'm not racing the car or driving it in the 5 - 6k RPM range, would it still be beneficial over the ported stock one? I thought the stock intake was good for upwards of 400 hp, which this car will never get to. Also, at the dyno, they asked me what to take the car up to and I said 5,000 RPM, I didn't want to risk damaging anything. Thanks everyone. BH
Yeah, its good to make a 500 HP engine run 400 HP, other than that it is a boat anchor! Its so heavy(how heavy is it?) its so heavy that it doesn't even need to snag anything on the bottom of the lake or river you're on to keep the boat from moving!
Curious, why is the torque so close to the HP number wise? And why does it peak at 4k? Don't stock and most modded SBB make peak at around 3k or less? Was it a chassis roller dyno, or that little dumb one they bolt to the studs? I've heard they read differently. Shouldn't it be around 70-100 more if that's where his HP is at? I always thought the drivetrain ate horsepower, and torque was taken up by gears and tire size...
Jumping in late on this thread, but I would also love to see this engine with the SP3 intake and headers (TA 1 5/8") . I feel the power increase would be dramatic. With these add ons, you should be making power up to at least 5800rpm. I would guess at least a 15-20hp increase at the tire with proper tuning
Probably a combo of the Gessler heads flowing so well upper rpm and the cam not degreed properly, or retarded. And needing timing to come in sooner. And a doubt that cam will spin to 5800