I aquired a 00 z28, Ms3 cam, ported LS6 heads, UD pully, SLP intake lid, SLP lid, LS6 intake, LT headers, Hooker 3" ORY, Fast Toys Ram Air intake, LS2 timing chain 42# injectors, comp lifter, MSD wires, .3.42 gears etc.

The guy I bought it from had it done... have dyno sheets.
with True Duals, the car dynoed 411 rwhp, 364 rwtq, To quiet it down..
he had put on a Hooker 3 inch ory, magnaflow muffler, and a retune, and it put out..
376 rwhp, and 333 rwtq..

Dos this sound right??

could the y pipe not be weldeed or put together in alignment and be robbing the power... this is almost a 40 hp loss and big 30 ft lbs tq loss.
maybe something else is wrong with motor before he had y pipe systme put back on... pushrod bent, valve bent, lifter bad..

what do you think?

thanks

 

The car was down on power in the first place, and a Ypipe definitely doesn't cause that much power loss. In some cases I haven't seen a peak rwhp loss at ALL going back to a Ypipe from a true dual, only some midrange TQ.

Have a professional check your tune. You've either got a tune or mechanical problem. Check and make sure the injectors have been scaled properly for starters..

 

something is wrong! you have no turque! how hi of RPM are you turning the engine? what is fuel pressure.

 

Ported heads? Looks like stock un touched head numbers(if that). Or your tune is way off. Dino sheets?

 

If your tuner did not do this for 42 lbers.... walk away and dont come back.

 

Thanks for thew reply, I've not taken it to a tuner, I live in middle Western Indiana, and it's a 3 hr drive to a tunner (Kocomo) or 1.5-2 hr to Crawfordville)

I believe he had it tuned at SLP around the Chicago area.. on the last tune.
I've rebuild many engines, but I;m afraid I'm kinda old school, and do not know what "scaled properly means for injectors".. does this have to be done by a tuner or can any auto shop do it.??

Thanks

 

I think hes talking about this. auto shop with tuning can do this.

 

I'm not sure, as the previous owner had it all done.

The car runs strong, but 333 rwtq seems low..

He gave me the papers of the dyno graphs, the first one 411 rwhp@6485 rpms and 362 rwtq@4694 rpms was on a Mustang dyno from straitline performance..(New Lenox, IL by Chicago)
even with the mods I think the rwtq is not too great.

After the 3in orY catback magnaflow setup, he had it retuned at and dynoed at FLP "Finish Line Performance" on a dynojet SAE corrected.

2 dif dyno's can be differnt, but darn those numbers between them are huge.
possible they didn't do the a proper tune..

Thank again

 

When I got my Jet-Hot Y, it had some nasty stuff at the
merge. Tube into tube, with about 1/2" of stick-in and it
looked like the one leg would prefer to shoot back up the
other side rather than out the back, due to some of the
"baffles" left by the manufacturing stick-in / slop.

You might inspect for this kind of poor construction on
yours, next time you drop the exhaust. Another Y I had
bought shortly before, had similarly crappy construction
in the merge.

But I would begin with the fundamentals, making sure the
other hardware is properly represented and that you have
reasonable delivered AFR and timing.

 

Regardless of the exhaust setup, 333tq is extremely low. Thats lower than a stock M6 with a lid.

I'm willing to bet most of your problem is in the tune. Can you post the dyno graph? How is the driveability? Does it buck/surge down low? Skip or "miss" through the rpm ranges?

Point blank, nobody is going to be able to solve your problem from behind a keyboard.
Regardless of the distance, if you want your car done right you need to take it to a professional tuner and have them look at it.

Or you can buy the software, buy a wideband, post your tune file, and people will be able to help you make the proper adjustments to get it close.

 

I don't have a scanner, might take a dig snap of it and post the graphs if they come out ok..

Thanks again, I have heard of good results from FLP for tunning in Napersville. but one never knows who tuned it.

I wonder if he changed plugs.
.. his 411 rwhp was around 4-07 and the 376 rwhp run was 6-07..

Wideband? wouldn't it already have a wideband if it has been tuned? I know there is two plugs coming our of the headers (probably O sensors)
I will have to take a deeper look, to see if one was installed.. otherwise it's big $$$.

Yes it bucks and surges down low sometimes...
runs good from a dead stop in drive mostly, but from a roll @ WOT will sometimes miss, buck (like fuel shutting down), and seem to go into neutral for a second and back...engine shut off for a second or so..
I checked plug wires last week, one boot was barely hanging on, back..#4
not much dif.. probably spark jumped before!

I know I need to probably take it to a tuner, but why drive 3 hours, and find out I have something else wrong, pushrod, valve bent, y pipe not flowing correct.. coil, injector bad..

Your tips are VERY helpful..

only change was from true duals X pipe into race muff dumped befoe axle.. to -- 3 inch ory into 3 in 1 in 2 out Magnaflow

should not have lost that much power even if they NEVER did a tune..
A would assume they would not tune it to make less power, after baseline run.. never know.
Soon as I get a mig welder.. I'm cutting the Y out and inspecting it.. Suspicious of it. .
even so if it is restrictive, it would not make around 376 rwhp,

The graph starts at around 4400 rpms has 270 rwtq
Torque at 4500 is only 300 rw
on the graph torque is almost flat 330 rwtq from 4600 to 6200
something is wrong .. like it will not allow more than rwtq after 4700 rpms..
I'll try and get a snapshot of the 411hp and 376hp graphs

Thanks guys

 

graphcs

411 hp (actually 395 corrected) true duals x pipe

Rpms for (411 rwhp) 395 hp graph are 2400-2830-3260-3690-4120-4550-4980-5410-5840-6270-6700
Hp graph is
0-40-80-120-160-200-240-280-320-360-400
as they are hard to see.

376 hp graph Y pie single muff

for Y pipe rwHP and tq graph rpms 3.5-4.0-4.5-5.0-5.5-6.0-6.5
hp is 150-200-250-300-350-400

 

The Hooker Y isn't the best out there but that shouldn't cause the hp/tq loss you saw. The CB might have caused 5-10 of the loss seen over the duals.

I have dyno cars with only 20" extensions on the headers than installed a properly built Y pipe and loss only 1/2hp up top but gain hp and tq down low.

 

I believe you,,,
But it was the only thing I know of that could have caused the car to lose the torque and power.. I think the Y connection is pretty primitive looking, could be a 1.5 inch hole in there going out one of the sides... one never knows who fabricated and welded it.
Another idea is the kid or guy I bought it from ran it hard, and maybe a bent pushron, valve bent (cam might not been decreed correctly.. it's 237-242 (?) 603-609.. lot of lift and duration.. need to do a cylinder pressure check for that.
I think it's both the poorly opened internal Y, and tune. 330 rwtq is not too great..

look here on this board same dyno

"Dyno Results from 3" Cutout Install (H/C LS1 with before and after graphs)"

https://ls1tech.com/forums/dynamomet...er-graphs.html

I'll bet he had a restrictive Y also.. he gained 20 ft lbs almost..
my car was 356 corrected and done to 333 corrected
the previous setup on my car befoe I had it was more or less open exhaust with strait through race muffs 3 inch dumped befoe axle.


I have a question on tuning.. does a person need to get a wideband before you go to a tuning/dyno shop? or do that have other means to check AF mixture @ rpms

I have much to learn on modern autos.

I checked the home tunners, "and lord!", to get started one needs almost $2000.00.. but the time you buy the pro version to do it right and be able to check and change AF mix, a wideband, and then a laptop.. having the wideband welded in..

Thanks

 

The dyno on the MD dyno looks like the converter is locked, where the dyno at FLP looks like the converter is unlocked.

 

put a cut out at the end of that y pipe... im sure you'll get the power back... my cut out gave me 20rwhp

 

something is deff. wrong. I have almost the same exact mods as you but im on stock 241 heads and I put down 393rwtq by 6k and over 400rwhp by 6400rpms....with hooker long tube competiton headers (1-3/4"), Shitty pacesetter Y pipe and stock SLP catback, Ported throttle body, 41lb injectors and upgraded valvetrain.

Im pretty good with tunes now. Do you have HP Tuners? can you post up the tune? I will check it for you.

have you ran it at the track with these lower numbers? It could just be the dyno. The trap speeds dont lie. If its trapping 115+ mph with stock 3.42's I would say your around the 400+ rwhp mark. I trapped 116 over and over again launching from a idle and bogging down on its face (2.5 60') with my stock 3.42 rear end. M6 as well.

 

Yeah, some guys say a good Y pipe will only lose 5-10 hp.. but who is to say I have a good one. it is a hooker Y pipe, but the construction doesn't look to well on the Y part. I'm suspicious .. going to get a good after marker high flow Y.. soon as I get me a MIG setup.
tks all

 

on a mustang dyno? sounds like good power to me. mustangs dyno's usually read lower

 

Yeah, Kidcam.. I've read about your car, and it is a monster.
Never want to pull up beside your car with nothing up ahead. might as well bow my head down in shame.. you have some power trapping 116-117
you have some serious rwtq..
I think ported ls6 heads can kill of tq.. seen someone else who had a set of porterd 243.. no low end power.

I wish I had HP tuner... been looking into it..
The pro version seems to be the only way to go to test air fuel mixture.
-what do you think?

with the cost of a wideband, and a laptop.. it will put me back $1,000.00-$1,500.00..


Thanks for the generous offer to help... I may get Hp tuner next year.
unless I could get one used. with credits.

thanks