Two different tuners on 3 dynos got the same results and it's the tune? Seriously?

I give the nod to low compression being the culprit; why so large on the combustion chambers?

 

My 414 with TFS 235 heads made 558rwhp 515rwtq. It made 485rwtq 3100rpm. I am using kooks 1 7/8 headers

 

I didn't think 11:1 was low. I see a lot of people running high 11's for compression but I needed something that could run on a road course for 30 minutes. From speaking with a few different engine builders, they recommended 11:1 for compression.

Will one of these setups produce more power than the other if they both had 11:1 compression? To me, it seems like they would produce the same power.

• Smaller cc/thicker head gasket
• larger cc/thinner head gasket

 

Sorry, I didn't do the math, it just doesn't LOOK like 11:1 looking at the numbers you posted for the parts... and I have seen many people upset with numbers after leaving compression on the table.

 

Data is from SD's site

Bore 4.067
ST = Stroke 4
RL = Rod Length 6.125
Number of cylinders 8
Deck Height (how much pistons come out of the hole) -0.005
Piston Dome or Dish (- for a dome + for a dish) 10
Compressed Head gasket thickness 0.041
Cylinder Head Chamber Volume 65

Static Compression Ratio 11.30 :1
Dynamic Compresion Ratio 8.71 :1
Rod to Stroke Ratio 1.53 :1
Bore to Stroke Ratio 1.02 :1

 

You followed the lobe of the week advice and with a bigger cam picked up a small amount of power without changing anything... that's what happens.

I can't see any miracles resulting from that switch.

 

Yeah, that's it. I picked the cam of the week.

 

Notice I said LOBE of the week.... not cam. So how much difference in power did you expect???? Too me it looks like you did WELL for that change. I don't know why you are

I know I've given customers smaller camshafts with lobes that have been around for over 10 years and they have seen more gains... actually for what you did you gained a good amount from that.

Bret

 

well somewhere power is hiding, just got to pinpoint where it's at. if the lg headers help torque without much of a restriction up top it is probably not the headers since torque is still quite a bit lower than expected. if scr is 11:3 going to 11:8 will only gain 10 rw or so(going by the 1 point scr is 4% more power give or take). i've HEARD those ti catbacks are restrictive on a strong setup so that may be some but definitely no where what it needs to be on par.

 

The purpose my thread is not to figure out why the new cam did not make more power than the old cam. This setup appears to be about 40hp/40tq lower than what it should. If it is lower than it should, I want to find out why. If these numbers are to be expected, than so be it.

Exactly. It seems like power is hiding somewhere. A few different vendors suggested the cam and headers were too small. It seems like a header swap to 1-7/8 may help on the top end but my low end torque will still be low.

 

Well I'll tell you from my professional opinion is it's not the camshaft.

Bret

 

I can say that's fact from experience.

Ron's right about the headers too. And the gears. Collectively, that's all worth a fair chunk of power.

 

I have a post in the Corvette section asking the same question about the TI's, and most said that there were no noticable differences. Have a look at some of the replies.

 

Well, I'm glad that everyone else here thinks it should make the power I told you it would. I'm not going to be any more satisfied as you until you actually make that power though. I want to see it perform like it should.

It's obviously not the cam. The original cam we got you and another custom spec cam from Ron didn't get you there, so there is no way it's in the cam. Swapping to Ron's bigger cam should have gotten you a little more than it did IMO and lost you just a little more low end TQ than it did. That fact alone means it's not breathing like it should be.

Overall, I think we KNOW where the power is. It's a matter of getting it by swapping headers, and possibly even running some cutouts. With the gears you'll always read 10 less than you could but I still think you can get 520rwhp to the wheels. It was a general consensus from the start that you need some 1 7/8 headers. Cutouts are good for 10-15rwhp over the Ti catback, so the catback can't be as bad as some people make it out to be, that's a relatively low loss for a catback. I also believe we discussed the gears causing 10rwhp difference on the dyno as well.

Pretty much all sponsors here agree. Headers and cutouts could easily be 30+rwhp, and you'll never see that last 10rwhp because of the gears. I think once you get some headers on there, you'll look back on all this head banging against the wall and wish you had swapped them out sooner.

Keep me up to date, I really want to see the numbers we know that engine makes.

 

i looked and well, most of those guys should know more than me since they actually have that exhaust but none said what the difference was compared to cutouts though. also was a guy with a h/c setup making 580 on a 100 shot through lgs and the ti system so i'm having a really hard time believing an 1 7/8 tube with cutouts will gain 30+ rw but hey ,stranger things happen.
good luck finding your lost power bro.

 

Don't have a scanner. Kooks 1 3/4....went back Tue and did 504/492.

 

I doubt very seriously you'll see 30-40whp from bigger headers and cutouts. I think you'd be lucky to see 10 and a possible loss of tq.

 

Doing my compression calculator with the above specs... I calculated the static compression at 10.77:1

 

There will be no loss of torque and the car dyno'ed today picked up 13rwhp with cutouts. It has the Ti catback as well.

 

i would expect higher....i made numbers in my sig corrected thru a dana 60 w 4.10 gears, steel shaft, 26lb flywheel dual disk mcleod, 1 3/4 headers, 3" y pipe and a stock slp muffler. but again dynos are just a tuning tool. take it out and run it and see what she does.