97SSdude

During this wonderful winter here in Wisconsin I decided to do a cam swap in my 1997 SS. I went with Lloyd Elliot for a custom grind cam 227/235 duration and 565/579 lift. Also did new lifters, dual springs, pushrods, and 1.6 SA roller rockers. The car also has long tube headers, ORY, and a GMMG exhaust. I took it to get a true dyno tune. Now here's where I'm shocked, they are still tuning it (supposedly) but did a run and the car only made 291hp and 313tq. Does this seem low to any of you guys. I was expecting to be well into the 300's in terms of HP. Could the shop be giving me a conservative tune and not really giving it a good tune. What do you guys think??

Fatdog2

Previous posts and dyno stuff says with your setup without the cam you should be pulling around 350hp.With a cam, around 429hp with a tune.I'm not trying to open a can of worms here but I've seen this in a hot rod mag many moons ago as well.
Intake,
long tubes
with a cat
Hope this helps.
Might seek Injuneers help on this one.
Post you car at the bottom of your messages that helps everyone a lot.

Injuneer

Did you only upgrade the cam? Heads not ported, still stock?

97SSdude

Yes the heads are stock. Nothing was done to them. I just think 291hp seems very low with a cam swap

Injuneer

OK. Just wan't clear.... the numbers suggested above, up to 429 rwHP with a cam only are not realistic. I thought I missed something.

You gained 30 HP and I would agree that is low. What kind of dyno? Is he doing the pull in 4th gear? How clean does the graph look above 5,000 RPM? Any sign of breakup?

And you told Lloyd this was for stock heads? I don't see an LSA figure, but he usually goes for the 108-110* range. The lower the number, the higher RPM to see peak HP. Did you install the cam straight up, or did he recommend something else? The lift seems on the high side for heads that pretty much stall at 0.500" lift, but I am not one to question Lloyd. Have you contacted him?

97SSdude

I have yet to pick the car up so I haven't had a chance to check out the graph or see what gear he pulled in. The shop uses a dynojet. I also have contacted Lloyd and he also agrees that the hp number is to low. He told me it should be between 340-360. My lobe separation is 110. I think it's a ****ty conservative tune.

Chimera96

typically DynoJet pulls show higher #'s than a Mustang....but yours do sound low.

if you could post the graph you will get some more specific comments

the run should be in drive or 4th if stick

also hopefully your AF ratio is shown on the graph

for a cam only tune with some bolt ons...a mail order from a reputable tuner would be good and likely show higher #'s assuming there is not a mechanical issue or cam install error

TGGodfrey

Did you degree the cam in? Just trying to rule out the timing being a tick off or possibly a grind error, it has happened.

Lifter Preload set properly? Any Chance you checked the final valve lift to make sure your pushrod length was correct? I have seen improper geometry reduce valve lift as much as 30 thous.


Did you discuss what you wanted out of the car with the tuner? I have seen tuners do conservative tunes on cars they expected to be street cars to avoid any problems coming back. Timing is usually where I have seen the conservative nature mostly.

97SSdude

I pick up the car either tomorrow or Tuesday so I'll post a picture of the graph then. I'm pretty sure the timing is dead on. The car runs great. Valve adjustment may be off a hair but not bad enough to cause that low of power numbers. I'll keep you guys updated. Thank you guys!

Matts97camaro

Something is off for sure. I would think you would be in the 330 /340 rwhp range especially with a M6. I made 309 rwhp/ 342 rwtq with mac midlengths, 160 stat, 3"ORP , PCMforless tune.
Car is a 93 Firehawk M6. Good luck and there is more power to be had from your engine for sure.

97SSdude

Here's the dyno graph with the AF ratio at the bottom. Tell me what you guys think could be a problem if there is one.

Injuneer

Almost looks like a curve for a stock LT1 with CAI and headers/catback.

If I'm interpreting the scale correctly on the A/F ratio, appears its a bit rich (12.5:1) at 5,000 RPM and above, except for the bump at 5.500 RPM. The bump to a leaner value in run 9 corresponds to only place where there was a moderate increase in HP vs run 0. He obviously had to lean it out fro run 0, but usually it will make best power closer to 12.8 - 13.2:1. However, that's not going to make up for the 30-40 HP it's missing.

Did he do the pull in 4th gear?

97SSdude

He did do the pull in 4th. I guess the only thing left to do is get another tune from another shop then? I mean besides the car being low on power, it still has a bit of a miss to it. Likely from the A/F ratio being off.

TGGodfrey

The problem with HP numbers and Dyno maps is that they are not all equal and vary all over the place from shop to shop. Not to mention your also receiving a tune to the shops atmospheric conditions. Your HP rating is also going to vary based on the fuel your running and the region you live in. Pump gas is not very consistant and the octane varies from truck load to truck load. Your elevation is also a big factor on your tune. Condition of your motor, injector condition o2 condition, drivetrain issues resulting in parasitic loss.... Far too many variables to say this particular setup is good for XXX HP. I wouldn't beat yourself up with it nor would I jump into another 500.00 tuning session without some track time.

Take it down to your local dragstrip and make some passes. Keep your slips and look at your MPH. Compare your MPH to others you see and a few members here. It is very possible his dyno is reading very low.

I would like to see your timing map. If the tuner didnt work with your timing map at all then that would quickly explain the lower numbers.

291Hp at the wheels isnt terrible for Cam and Exhaust. 429 at the wheels is a pipe dream without headwork. My 94Z had a grantelli Charger on it and that was 407 at the wheels with factory motor and 6lbs.

Injuneer

The curve clearly indicates it is corrected to SAE standards, eliminating the shop's atmospheric conditions and elevation. Fuel differences by region are not going to cause what appears to be at least a 10% shortfall. Sure, running it at 87 octane at sea level would be a valid concern. The use of the wideband, and the fact the PCM does not use the O2 sensors for PE mode eliminate bad O2 sensors.

Condition of the motor and parasitic drivetrain loss differing from normal are things the need to be investigated.