bww3588

iTrader: (49)

here's the low-down.

i have a 98 LS1
MS4
TSP PRC 2.5 5.3's milled to 58cc's with Cometic .040 gaskets ~11.5:1 comp
Mahle forged pistons with 4cc valve reliefs
39lb injectors
stock rockers.
LS7 lifters with 7.350 TSP pushrods
LS6 intake with ported stock TB
Edelbrock LT's 1 3/4-1 7/8 3 1/2 HVMC's
temporary spiral flows right off the headers
SLP lid

suspension wise im running a tunnel mounted TQ arm. its an older one, im not 100 percent on the brand, a Sphon sway bar out back, Eibach drag lunch springs, and BMR non adjustable control arms.

i have a stock T56 with a moser 9 inch with 4.11 gears, and for tires at the track im running Hoosier QTP's 28 11.50 15's. i dynoed it on the street tires tho....

anyways, numbers were 367hp and around 390 TQ at the wheels. power was peaking at 6700 rpm's right were it should.

and track times were 12.39 @110 with a 1.71 60'.

i did a compression and leakdown test on it. its 245lbs on all 8, and ~5% leakage on all 8 past the rings to the crankcase.

its been tuned on the street as well as the dyno, it still has some bugs as far as driveablilty, it dies sometimes at stop lights and still has cam surge at low RPM's. it also runs pig rich when you first start it up. im just seriously dissapointed with all the numbers for my mods....any ideas or help would be great.

blown03mustang

sounds like you need a retune...id say find a better tuner

whats your a/f ratio look like? got a dyno graph?

bww3588

iTrader: (49)

is there around 100 hp just laying around in a tune?

JScamaro

iTrader: (6)

First I would have someone else look at the tune and get the bugs worked out. It shouldn't be dieing at stoplights.

badazz99ta

iTrader: (13)

im casting another vote for a tune. im not saying that will solve it. but its a good place to start. good luck man.

Jrp1978

iTrader: (10)

Tune for sure ! I am curious to see your graph if you have one ! also with your heads being milled you neeed to go that low on a pushrod ? You have any valve train noise other than the normal sewing machine sound !

navyblueSS

iTrader: (1)

I say tune as well.

PREDATOR-Z

You are making 367hp/390tq, that is impossible with that cam unless something real wrong. HP always higher than tq with that type of cam spec and high durations.
Unless it is a typo and you are at 467hp
In that case you should be well into the low 11s with proper suspension and driving skills on full weight. Maybe even 10s

ssvolvo

Not that this will help. But I have the same heads as you, and Cometic gaskets but TSP 220r cam (small) 220 duration@.581lift. Stock ls6 block, internals. Homemade long tubes thru cats and 2- 3" inch Magnaflow mufflers single 3 inch exhaust. GTO LS2 intake manifold open element air filter with 06 GTO elbow (ribbed). In a Volvo that weighs 3200 lbs. Thru a 4L60 stock converter from a truck. Dynoed last week thru 215 street junk tires at 368hp-342tq. Peaks at 6100rpm hp and 5100tq. My leakdown test last week shows no more than 5% all cylinders even. Didn't check compression but it must be high because I can only run 20-22 degrees timing@WOT without knock retard on pump gas.

Made 10 runs yesterday runs consistently 12.40s @114-115 on same tires.

I expected more at the dyno but less at the track. Start with the tune. Careful with the timing. 12.5-13:1 fuel that should be a start.

Patrick G

iTrader: (14)

First off, your pushrods are too short. Second, without seeing your graph, it sounds like you have a dead hole. It's either no fuel or no spark. A balance test will help. Your tuner should be able to perform one.

Mike TexaSS

iTrader: (2)

M6+MS4= at least 390 rwhp with headers. Something is wrong.Did you do the install yourself? If so take it to a professional and have them look over everything.


Patrick the torque number seems right the HP just isnt there. So I dont think its a dead hole. Might be valve float.

bww3588

iTrader: (49)

ill try to answer all questions here.

i know its not a dead hole, i did a power balance test on an o-scope, all cylinders are contributing evenly, i didnt get a chance to print the graph when i dynoed it, as there were other people wanting to use it and i kinda got kicked out. i ran with the shorter pushrods because the heads were milled and i used the thinner gaskets. when i checked them, the 7.350's were the closest i could come up with on the checker. also, i installed the 7.4's and every valve opened on TDC on the compression stroke a little bit. so i figured thoes were too long. i built the motor myself, the cam is installed dot to dot. im going to go back to the dyno here in a few weeks and see if i cant get some time to myself on it. i have access to it whenever i want so its kinda easy.

lmk if there is any other information you need on it.\


also, about the valve float, i had valve float issues the first time i dynoed it and it was putting down 344hp but at only 5600 RPM's. so i bought new valve springs and put them on and it took it up to around 6500 ish RPM peak. but it only picked up around 20 horse.

fauslpss

iTrader: (6)

Well one maybe you should of degree'd it instead of "DOT 2 DOT" there might be some there.

I doubt its the PR's.

Eric

Patrick G

iTrader: (14)

LSK lobes require longer pushrods than XE-Rs. When you mocked up the pushrods, did you find you needed different length pushrods between the intake and exhaust valves. What is the installed height of your springs? What springs are they? The reason why I mentioned pushrods in my first post was LSK lobed cams require very careful spring/pushrod setup...otherwise, you can run into valve control issues. Can you post a graph so we can see your power curve?

jsteele90

iTrader: (13)

wow all i can say is wow. your tune is seriously hiding some major hp

bww3588

iTrader: (49)

i was not aware of this. i dont have a graph, here in the next week or so im going to take it back to the dyno, that is if i can get some time on it. im going to tear the heads apart here in a few weeks. i've decided, im going to tear the motor down again and build it for nitrous. im getting the adjustable timing set, everything is going to be blue printed down to the finest spec. im sick of the bs, i want a bullet proof motor. however i still want to get to the bottom of this, just for peace of mind issues as well as to help people on here having similar problems.

lemons12

iTrader: (71)

i have ms4 and ported 90/90 full exhaust 4000 stall 410s... i dynoed 385/338 on a dyno that dynos about 20 low... remind thats an a4...

i ran a 7.5@90 in the 1/8

it shouldnt be dying or surging with a good tuner.. mine drives perfect on the street.. 50 miles or so a day

send your comp to tsp

Datzneat

iTrader: (4)

Wow. I hope you get this figured out man.

qwikz28

iTrader: (12)

+1 for checking pushrod lengths. i used to have a torquer 3 (similar cam only with lower duration) and something was screwy with the pushrods but a local specialist squared it away for me. i picked up a very good amount of power afterwards. do you have any weird ticking noises coming from the engine bay?

2xLS1

iTrader: (25)

245 lbs cranking compression seems way too high for a MS4 cam's valve events.