Dubai944

All you dyno gurus might like to help me make sense of these charts and contribute to my self rambling. Feel free to tell me I should get a turbo or a V8 if it makes you feel good to say so...

This is from the latest round of tuning just completed today on my supercharged 3.0. Current specs are S2 block with piston squirters, 968 head, Arrow rods, Wossner pistons 9:1 compression, big duration NA cams, stock 968 throttle body and intake. 72lb/hr injectors. Stahl headers 2.5 inch exhaust. Procharger C2 head unit and stock turbo intercooler. Tuned with a MoTeC stand alone.

The first chart shows power against boost level. I'm sure all you turbo people will be underwhelmed - barely 10psi, but it's nice and linear and repeatable. Belt slip has been eliminated with an 8 rib pulley setup, heavily modded braced bracket and a tight dual idler pulley setup which wraps the belt very closely. There appears to be no belt slip at all anymore and the belt stayed cool and tensioned through two days of tuning.

So my first question to myself is why is the boost level flattening out at about 6000rpm. I have geared the supercharger to run at it's maximum design speed at the set rev limit of 7500rpm which I occasionally run to in the heat of racing. This is spinning the head unit much faster than the standard gearing used in any of the kits. The gearing has helped raise the boost levels down low which is good for a centrifugal charger, but in theory the C2 can flow 1100 cfm of air, so could it really just be running out of efficiency so early and just be too small? No compressor maps available from Procharger of course so unlike a turbo not much chance of scientific assessment.

I have gone a far as I am prepared to go making sure the supercharger can do it's best. Maybe it's just the inefficiency of the stock intercooler, or the intake manifold. Maybe the 928 motorsport boost limit valve which I have screwed completely shut is still opening slightly anyway and limiting the boost. Hmmm... probably no real answers to the maximum boost question apart from get a turbo!




Anyway power level is acceptable and the torque curve is reasonably flat (see the second chart) so performance should be where it needs to be on the track. Next question is the torque values. The curve looks ok but for some reason the chart scale is in dyno load of Lb. what does that mean to me? The third chart is apparently the calculated flywheel values (probably not very accurate) but at least shows torque in Ft/lb. I'm confused though, does any of this tell me torque at the wheels or do I have to manually calculate that from the first hp chart. Probably.





One other interesting things from this session was that I asked for a run through the range with the variocam off and a run with it on all the time, hoping to show exactly where it was helping and where it wasn't. I didn't get the charts but was told it made no difference at all wherever it was activated /deactivated. Maybe that's because with the big cams it doesn't help at all, but I would have thought 15 degrees of advance would have some inpact positive or negative somewhere in the range. The tuner seemed pretty switched on so maybe it's not even working...another head scratcher to sort out!

333pg333

All I can say is wow Steve. Assuming this is hp to the wheels as most Dyno Dynamics charts register? If you're getting 425whp at 10psi....well that's probably a record around here. Even 362whp is excellent. He is running it on a more aggressive ramp rate 'RR:015' but still, I got something like 385whp at 23psi at the same ramp rate. Wiser people than me will give you better feedback but I'm sure your car is plenty fast.
Oh, yes, you do need to do a calc to get the torque but it looks like he's changed it to ft/lbs in the last chart.

Dubai944

Pat, 362 is the whp. The last chart of 425 is just a flywheel estimate.

333pg333

It's still very good at only 10psi. Is that with the stock pistons and c/r Steve?
Are you thinking of upping your power somehow and trying to decide? I 'might' have an option for you...

Dubai944

Wossner and 9:1.

Well 362whp on a dynodynamics is about 40hp up on where it was before, in theory. The torque curve is still nice and flat so will be interesting to see if it actually drives much better..

That is if it ever stops bloody raining in QLD so I can get out to the track.....lol!

Zeff

My old roommate had a Procharger F1A on his mustang... I remember him telling me something about hitting the max pully boost level. Like you hit what the pully is setup for and it will peak out. I don't know 100% but that might be something to check out.

gruhsy

3 inch exhaust 2.5 not flowing at top end???

blown 944

I think the inter cooler is probably the bottleneck. When I did a lot of testing I found it to heat soak quickly and lose efficiency. It would be telling if you had an ait gauge handy.

Darn good power out of that thing. You could do a methanol spray at set rpm and boost and I bet you'd pick up 40-50 hp

DDP

Very interesting setup. Superchargers weird me out so I don't have much input here other than I'd love to see pictures of the engine setup. Also, if you're only running 10psi, why not bump up the compression a bit more? What gas do you run?

Dubai944

Interestingly I had a 3 inch straight through with a single muffler on it that was so noisy it wouldn't meet the noise restrictions at most tracks. So I had a quiet exhaust made in 2.5 with three spriral hot dogs and a standard hot dog. You would think it would have strangled the engine, but both systems were tested back to back during this tune and it made a total of 3hp difference. Go figure!

I have read in a few places that the standard intercooler is limited. I even read one guy who said he gained 20hp by removing it altogether, so maybe there is something in this. Trouble is it is a PITA to change the type of intercooler now all the ducting is set up. Can the stock cooler be improved much? I know Lindsay Racing offer a modified version, but no idea if it works well.

I like that idea! I could add a "Go-Baby-Go!" button to the dash.


I'll post some engine pics shortly, but I haven't spent much time making it pretty so don't be dissapointed..lol.

Just running on pump gas 98 octane. I chose 9:1 compression originally because I thought I was going to be able to make 1 bar of boost from the Procharger, but haven't got there yet. I also wanted the motor to be ready to go if I did decide to eventually turbocharge it and push the boost way up.

dand86951

My experience was that even the Lindsey Stage 1 intercooler helped. I didn't have before and after temps but I did see about 3-4mph extra speed at the end of a straight on a track that I had a lot of time on. This was in my 951.

Note for some reason your dyno charts aren't showing up on my screen.

dand86951

Edit, well now they are there, good results!

mudbuddha

Good hp/tq number I thought- I like the area under the curve and boost came on pretty early too. The charger maybe maxing out on its efficiency as does the intercooler heat-soaking at that hp level. 98 pump is like 93 in the US no? So race gas and better intercooling would net another 15rwhp or so...Mines needed 2X your boost level on pump to net 380 to the wheels and also believed that I am maxing out on factory intercooling efficiency as well. I am interested on some feedback from those with upgraded IC...Overall good numbers, should be quite fun on the track I would imagine.

DDP

Unless you're seeing a significant change after each dyno pull, I wouldn't suspect the intercooler. I'm not saying that it's the best you can do, but stock IC's seem to flow just fine for pretty high HP and so the only other reason why the IC would hurt you is if it was heat soaked. On the first run, though, it wouldn't be heat soaked. Then you would see it affect the numbers as the pulls went on. I bet it's just the supercharger. Can you find more info on it? Possibly other cars running it?

10 psi isn't much for 9:1 compression. Although, I must say those are impressive numbers for 10 psi.

azbanks

333 and mb, are you running 3 liter 16 valve engines or 2.5 liter 8 valve engines?