Help! HUGE disappointment at dyno 324 Hp and 372 FT LBS. torque

[MYSC351]

Not at all what I was expecting. Figured I'd be in the 400-450 HP range at the rear wheels and close to that in torque....I'm truly disappointed.

My engine isn't running right

For my engine set-up I've got

Engine Mechanical:
351W D.S.S. block bored to 357.. converted to a roller block..2 bolt with a girdle
Compression on the block is 9.4:1
procharger D-1SC supercharger running 12 P.S.I. boost
Edelbrock heads
Edelbrock performer intake
75 MM Throttle body
3" equal length headers and 3" hooker header exhaust system
Cam is MILDLY ground
GROSS valve lift--intake .566 exhaust .576
Duration @ .020 intake 284 exhaust 289
Valve timing @ .050 intake open 8 BTDC...close 44 ABDC
Exhuast open 58 BBDC.close 2 ATDC
specs for cam installed @ 111 INT
DUR At .050 Intake 232 Ehxnaust 240
Lobe Lift: Intake .354 Exhaust .360
I run 93 Octane non-ethenal fuel

Spark:
MSD 6L spark box
MSD blaster coil
High performance 8.8 wires
MSD distributor
NGK racing v-power plugs (((I think these plugs may be the problem, but that's what the previous owner was running in the car.))))

Fuel: F.A.S.T. fuel management system..(Computer)
aeromotive fuel pump
aeromotive 83 LB injectors (a little over kill)
aeromotive fuel pressure regulator
I've got the fuel pressure running @ about 40 P.S.I. When I lose engine vacuum it jumps to 60 P.S.I.(for the supercharger)

Here's a picture of what I'm running.

Now for the problems I am having and what I've done so far...
To start I never had this problem when I bought it, it's only recently started to show it's ugly face..

Originally I had a bad misfire @ 5200 RPM and saw my fuel pressure gauge drop while it would misfire......I removed my vacuum hose from the pressure regulator, and it turned out the pressure was dropping due to the engine misfire creating a vacuum...So fuel pressure IS steady during the misfire.
Next I swap in a new set of plugs gapped @ .029....The problem got worse, I had misfires all the way down to 3800 RPM...
Next I installed plugs @ .031.. The problem @ 3800 went away, but a new problem has developed....

By this time I've given up and taken the car to get dyno tuned as I beleive it is an A/F issue...The dyno shop calls me back and tells me they put the car on the dyno and it ran fine...Test results????324 HP and 372 FT. LBS. torque....
I think ok great, so they couldn't get it to act up.. I'll just drive it until it does and take it back for a dyno tune and diag....I get it back and drive it for 2 miles...The car is shaking like hell @ WOT and running like crap....The Dyno shop "Road tested" the 4400 LB car on the dyno...It didn't act up because their "road test" was on a dam dyno....

Determined to tackle this problem I again pull the plugs, this time do a compression test and install a new set of plugs with a .032 gap...The old plugs where FULL of carbon with just 800 miles on them.
Compression results are as follows 4 cylinders @ 152 P.S.I. 1 cylinder @ 150 P.S.I. and 1 cylinder @ 148 P.S.I.....So the compression test shows good results..
I install my new plugs and off I go...Immediately after starting the engine I found I have 1/2 second delay in throttle response... I hit the gas on the relatively cold engine again...no throttle response..it takes forever for the engine to rev after opening the throttle..I let the car warm up to operating temp and it begins to run like a raped ape with great throttle response...
So I go for a test drive..Everything feels smooth and it feels as though it's pulling pretty good...So I get out on an open road and open up WOT..

Same thing as before..During WOT acceleration the engine "shudders" and has less pull than it should...It doesn't have no pull, just not as it should.....

I know that the "shudder" as I explained it sounds like a driveline issue...The reason I know it's an engine shudder, not a driveline issue is this..

1.) The shudder only happens under boost.
2.)The shudder only happens under 100% WOT..If I accelerate thru the gears @ 3/4 throttle I actually have just as much (if not more) power than I do @ WOT...with NO shudder.

I would think since I have no shudder @ anything other than WOT it must be a tuning issue correct?
I'm kind of at a loss here.. I can accelerate to 4000 RPM then go 3/4 throttle and it will accelerate like it should @ 3/4 throttle quickly to 6100-6200... Even from 1000-4000 RPM @ 3/4 throttle it accelerates great with no shudder...But I can be sitting @ 2800 RPM's where my power band begins or @ 5000 RPMS in the top end of my power band and it won't matter.. As soon as I go 100% throttle the engine shudders? I really don't get it and am at a loss right now...My next step is to get ride of the NGK racing V-powers and get a set of regulaur NGK racing plugs..
(of course copper is the only way to go)..

Any help is greatly appreciatted? Where do I start with this mess? Why only @ WOT under any RPM??

Is anyone else running a simaliar set-up?? What dyno results are you getting?? What E.T. times??? I know this is a 4300 LB convertible, plus the added engine weight, rollbar, ground effects, driver, etc make it 4700 LBS going down the track and that will kill my time, I'm just curious for comparision purposes.

 

[enyawix]

The first thing I would do would be install a air fuel gauge. Get your air / fuel mix under control. I would also keep a very close eye on the spark plugs. Your injectors look a little BIG for your setup, I would put injectors that BIG to good use by changing to e85. e85 needs 30% more fuel, but is much more forgiving as far as tune. Also keep an eye on your fuel pressure.

 

[5spd GT]

Is that camshaft custom?

What valve springs do you have?

Good Luck with the fix.

 

[347HO]

My first impression without being there "first hand".
1. You installed 302ci parts on a 357ci sbf.
What I'm getting at is your cubic inch wants to breath and you're choking it.
2. In my experience, that shudder at WOT are improperly setup cylinder heads. I can't even
guess what it could be since there are more than several causes for that. My first impression again would be your air charge is experiencing instability from either stalling, or sonic choke, to even a type of reversion in the plenum of the intake.

 

[enyawix]

Is that camshaft custom?

What valve springs do you have?

Good Luck with the fix.

I was about to ask about the cam but, I think the tune is bad.

 

[MYSC351]

enyawix: I agree those injectors are way to big. The engine tune is exactly the way I bought it...My laptop doesn't have a serial port, so as soon as my serial/usb adaptor gets here I'll check pulse width, 02 data, etc...I have a few exhaust leaks right now, so the 02 may be off...
E85 is scarce for the consumer in the part of Iowa that I live..Government vehicles have their own filling stations, and 10% is everywhere. But no luck on E85 locally....Plus we could discuss advantages/disadvantages of ethenal all day long...Personally, I don't really care for the BTU rating of ethenal and the amount of fuel required to power the vehicle...I know it has advantages such as higher octane, etc. But E85 isn't for me....(That is another debate for another thread and could easily go pages and throw this post OT in no time, so I'll leave it at that.)

You mentioned an A/F gauge..I have a wideband 02 and once I get the serial to OBD adaptor that I ordered from FAST I'll be able to data log it.....What advantages does an A/F gauge have over the 02?

I guess I'm not oppossed to an A/F gauge as it would be easier to monitor than data logging...Where do I get one? How does it measure my A/F ratio? Spark plugs are fouling like crazy...I'm pretty sure I'm running rich..Like I said with the new gap I have no throttle response while the engine is cold...As far as fuel pressure, it is not running lean due to lack of flow...My fuel gauge is plenty high.

5spdgt: I beleive the cam is custom ground. Like I said I bought the car exactly the way it sits..The guy has most all the recipts in a book.. There are several parts from comp cams and ford racing including roller rocker arms, hi-tech push rods, roller lifters, etc....There are two part #'s that don't crossover on compcams website, so I'm not sure what they are...
One is 35-000-8RF...I'm going to assume this is a custom cam part #, but I'm not certain.
The second # pulls up a part on campcams website, but doesn't give a description..978-16.

As far as the valve springs, I'm not sure. I don't see a receipt, but I'm going to assume they are stiffer springs...He replaced a bunch of stuff, I couldn't imagine he would have kept the original springs....
EDIT: I just checked summit's website again and it shows valve springs included with the performer RPM heads, so I'd say they are Edelbrock valve springs.
The gauge cluster was replaced when the engine was and shows 5800 miles...5000 when I bought it, so this set-up has 5800 miles on the rebuild.

347HO: That makes some sence..It explains alot, but doesn't answer why it ran great for the first 400 miles of ownership...As far as the heads go, I forgot to list they are Edelbrock Performance RPM heads...Reason for the delay in reply is I was looking up the specs on the heads..I'm not sure which model Performance RPM heads they are, but I checked summit and it looks like they are all have 170 CC intake runner volume and all have 1.9" to 2" intake valve diameter... Do you think this is not enough?
The sonic choke would explain alot..I'm trying to figure out a way to run the intake closer or inside the scoop of the hood.....I'm buying a longer hose to bolt onto the supercharger inlet tomorrow and am going to stuff the filter inside the scoop. Right now the guy has it laying right on top of the valve cover..(Look where the tube ends in the picture above..I had the filter off in that pic, but you can see where he had it laying)..I know all that heat from my manifold is killing...Is there a way to confirm this is my problem by checking my 02 during WOT? Any other ways of confirming this is my problem?

EDIT: Also I am having a problem with a very slow crank after an extended drive (30-45+ minutes) I checked voltage drop across the starter to the engine block ground. there is a 9 volt drop while cranking.... I checked battery volt drop across the terminals while this happens and I also found the battery drops to 9 volts....so the voltage drop across the starter is source voltage, indicating there is no bad wiring....Even with a 75 amp charger hooked up and battery voltage @ 12.9 volts the battery drops to 9V during this very slow cranking....I assumed the starter was drawing WAY to many amps due to a faulty starter...The only reason I mention this is I'm wondering if the starter is having a problem cranking the engine due to the engine having to high of pressure...Does this make any sence or am I WAY off on my theory?.Like you said if it's struggling to move air thru the heads??.. As soon as I take the car out for an extended drive again I'll attempt to crank the engine by hand to see if it is the starter or the engine being hard to crank.

Thanks guys for the quick responses..I wasn't sure what to expect, I'm very impressed with this forum.

 

[enyawix]

I missed that it ran great for first 400 miles of ownership. I would check for vacuum leaks, look at cap and rotor, check the pick coil, check the ignition control module at advance or auto zone, and check fuel pressure. A small exhaust leak would not create all of your issues.

 

[347HO]

You have a 1:1 ratio FPR installed or something to increase fuel during boost?

I totally agree with wix... something came loose, and it "reads" like a vacuum problem.
Also double check to make sure your distributor is locked down.

 

[SadbutTrue]

You should definitely look into a Performer RPM series intake. With the carb versions at least, the 351w version of the Performer sucks, terribly.

I do believe you have some tuning issues beyond just the intake though.

 

[oz]

Just going back to basics here - when I built up my 5.0 and ran it for awhile it started bucking, pausing before accelerating etc... I had two burned plug wires that would fire at idle but would arc to the headers under load. Equal length headers are hard on wires. Just make sure you don't have the same problem I did.

I don't know what kind of mufflers the car has but I had fiberglass filled mufflers back in high school that failed and pluged the exit of the muffler... car would run but not very well. If you're running rich you could melt enough fiberglass to allow it to enter the outlet...

Since you've already ruled out a compression issue, it's either fuel or ignition related. The fact that your plugs are black right away tells me you have a fuel issue - way too much of it. Get the wideband O2 sensors working and start tuning... You'll score the cylinders if you run rich for too long so be careful.

 

[SQUEEZE&STROKE]

Sounds like way too much fuel...also, the plug gaps are questionable. I had a very similar issue in my Lightning...turns out the plugs were gapped to large. I think both are contributing to your problem.

Try NGK TR7's...IIRC.

I put those in the L and with the correct gap, they worked awesome.

 

[1BADLXCOUPE]

Yo Fella's. Lets look at the basics here. A NON MODDED, Factory 302 H.O. Engine could easily hit 324 RWHP with a D-1 Procharger, let alone a decked and tricked out 351 Windsor. Your Tuning is Extremely Off, If it is a reputable shop they would know this and would atleast help you solve your problem. I feel the problem lies with the Injectors and the ECU, maybe even the Spark Plug gap like someone noted earlier. I'm no engine builder but I really feel, the best thing to do right now, would be checking your code's and do a standard rundown from there.

 

[5spd GT]

I do not see the "302 parts on a 357" being a problem at all, in this situation.

Korey (above) has got a point. There is something with the tuning or mechanically wrong.

Unfortunately, that encompasses many potential problems.

 

[2002BLGT]

First thing I would do is pull the distributor itself and put in a stock replacment one that will work with with the 351 swap ........those MSD distributors are well known for causing untraceable problems

 

[2000xp8]

It's about 200rwhp off, something is seriously wrong.
I'd suspect it's the standalone system. Which in most situations it's better for the professionals to handle.

If all you are expecting to run is in the vicinity of 500rwhp, at least drop down to 60's.
The sale of the 80's would fund the purchase of smaller injectors.

 

[bt15]

I would be looking at ignition for a few reasons. Ignition module problems could account for not only the running issues, but the starting ones, as well. In fact, I had very similar problems (though on NA engines) in both my 351 Bronco (turned out to be coil), and my 85 Twister II (ignition module X 2). Symptoms were similar to yours both during start and WOT. So, if you have a spare module and / or coil lying around, you may want to try ruling them out before you dump a ton of cash into other theories. I'll warn you that it's very difficult to bench test modern CDI boxes unless you have some pretty decent knowledge of the systems. Accel took back my box for testing twice and gave me the thumbs-up both times (which led me down a very expensive troubleshooting path). Finally, I threw on a stock Duraspark since nothing else was helping, and all my problems were cured. I sent the box back to Accel again, and they finally admitted that the box was bad.

 

[347HO]

I do not see the "302 parts on a 357" being a problem at all, in this situation.

Although the smallish intake and cylinder heads "may" not be all the problem here, you and the OP should research the physics of fluid dynamics and the association to speed and pressure changes when passing through a duct.
I understand what you're getting at with this application being forced induction, yet the air column will still be affected by the small cross section of the cylinder head. More cubic inches, more air will be moved at the same rpm (piston speed) when compared to smaller cubic inches.
More air = more power.

Korey (above) has got a point. There is something with the tuning or mechanically wrong.
Unfortunately, that encompasses many potential problems.

You're being vague... what aspect of the "tune" are you suggesting?
What I'm saying is; of course it's in the tune. Step up and point your finger at something.

 

[5spd GT]

Although the smallish intake and cylinder heads "may" not be all the problem here, you and the OP should research the physics of fluid dynamics and the association to speed and pressure changes when passing through a duct.
I understand what you're getting at with this application being forced induction, yet the air column will still be affected by the small cross section of the cylinder head. More cubic inches, more air will be moved at the same rpm (piston speed) when compared to smaller cubic inches.
More air = more power.

Pretty basic stuff right there Dana.

I agree completely here. However, there is no need to take up for your comments. You and I both know that that car should be making a considerable amount more power, even with the top-end pieces.

That was my point, strickly.

You're being vague... what aspect of the "tune" are you suggesting?
What I'm saying is; of course it's in the tune. Step up and point your finger at something.

No, I am not going to get specific about something I am not familiar enough with to comment accurately on something over the internet.

However, (again) I am very aware that it appears to be a tune issue (possibly a blend of mechanical issue), considering the amount of HP it is off from other typical combinations.

 

[347HO]

I read more clearly where you're coming from David!

 

[Bullitt347]

How much ignition timing is the engine seeing? If it has to much advance the engine will be fighting itself when under load/wot. 3/4 throttle does not produce near the same load on the engine as WOT. So one could get away with to much ignition timing at 3/4 throttle but have a big issue at WOT. I would guess that 26-28 degrees of total timing are all that are needed for a "safe" tune with your combo. To run any more than that would require more dyno time and a working air/fuel meter among other things.
My 2 cents on the cylinder head/intake issue. On the inlet side it is really a non issue as the runner ect is under pressure with boost and will offset the "smallish" runners/valves ect. Of course bigger heads will make bigger power on the top end, but the only real issue would be a small exhaust port/valve on a boosted engine, as the port and valve can only efficiently remove so much exhaust gas before it starts to load up the intake side of things. That would be a problem. My friends 331 engine makes 625 rwhp with a AFR 185 cylinder head and 17 psi boost. With the AFR 205's the engine would make more power, but it certainly does not have a WOT issue! Again, my 2 cents worth for those who care.