Just Dynoed, runs out of air @ 4650rpm!

[jballa]

I thought I had my car where I wanted it and a dyno tune would fix everything and give me the top end power I've been craving....

Not so.... The torque was great at 350 ft/lbs @ 4500 rpms and the power curve was on its way to 375 RWHP @ 6000 when around 300 HP @ 4650 something depressing happened! It just stopped making power... The guy at the shop said my restriction is in my heads (world windsor jr. iron) b/c everything around it was made to build power. He also added a quick fix would be a 200 shot NOS.

What heads would work well with a 331 N/A 10.4:1 stroker combo to make 375+ RWHP and gobs of torque. I hear a good porting should be necessary too? I have access to a flow bench so we'll see how much difference a porting will make.

Thanks in advance!

 

[86bluecobra]

what cam are you running? Are the valve springs matched to the cam?

 

[jballa]

92 Mustang coupe, 331 stroker w/ 10.4:1 compression. 30#injectors, 190 lph fuel pump, msd coil, bbk ssi intake, cold air, cc 1.6 roller rockers, World Windsor Jr. iron heads, Diablosport chip, shorty headers, deleted smog, high flow cats, flowmasters, 70 mm TB, 73mm MAF, SRP forged pistons, 5.4” H-beam rods, 4340 steel crank, balanced @ 28 oz, billet steel flywheel, etc.

Lunati Custom Cam 110/118 lobes, .548" lift, 230/237 dur. @ .050

Also, I don't think the SRP flat tops will work with some heads-

 

[88mouse]

I don't think your problem is in the heads. Those heads make good power and flow pretty good.

 

[jtfairlane]

I would take that Nitrous recommendation from your dyno guy with a grain of salt. I'd be really hesitant to run any kind of power adder like Nitrous or a blower with 10.4:1 compression.

 

[Hickfied]

I wouldn't run a blower w/ that much comp, but i'm getting ready to run two stages of 200 shot (400 total) on my 10.7:1 engine.... But don't use the nitrous to make up for what you really want.

 

[jammer84_03]

u need more duration!!!!!

edit: at 50...didnt read that after...sry...lol

 

[Mr. Rustypwnz]

just port the piss out of the heads, a 200 shot is overkill, what block do you have?

 

[85_SS_302_Coupe]

You didn't mention anything about valve springs....4k is around the time that your going to see valve float if you don't have enough spring to back up the cam. I would be willing to bet those heads came with springs to match about a 500 lift cam..

 

[BlooDReigN]

Yeah...something is definately ****ed up if you are making peak torque at 4500 and peak hp 150rpm later....85_SS is probably right on the money with this.

 

[Mr. Rustypwnz]

depending on what jr. head you got, its either .560 or .600 lift springs that come with the assembled heads, so I would say you should be fine on valve springs!!

 

[jballa]

The block is stock bored .030 for the stroker kit. The engine was done professionally by a highly recommended engine builder who changed the springs for the cam, but I don't know the exact weight of them.

Something is definately off b/c the curve starts on a downward sloap of torque and power around 4600 rpms... How could I check for valve float.

I know a blower won't work, but a shot of NOS would be ok i think... It makes since that its running out of airflow when you look at the curve.

 

[795.0pacecar]

Post up all of your engine specs/mods. If I remember right valve float sounds kind of like a rev limiter.

 

[slappy9090]

AFR 205!

 

[66Runt]

.

 

[jballa]

Actually the cats glow red at night, but I have to have them for inspection.. they are new high flows so I guess that's the best I can do? I'd expect more restriction in the shorty headers anyway.

As far as the valve float, it would be evident with high RPM's sounding like a rev limiter - that does not happen, especially @ 5000 rpms.

The gaskets are made for the BBK SSI intake along with the plenum spacer. All 3 align from the upper to lower intakes. Does anyone else have dyno experience with this intake?

I have to find a scanner before I can post the dyno chart, but I'll do my best to find one.

Is it common agreement that the heads are not my problem? Windsor Jr.s out-the-box would be capable of more than 300 HP?

 

[2002BLGT]

Actually the cats glow red at night, but I have to have them for inspection.. they are new high flows so I guess that's the best I can do? I'd expect more restriction in the shorty headers anyway.

As far as the valve float, it would be evident with high RPM's sounding like a rev limiter - that does not happen, especially @ 5000 rpms.

The gaskets are made for the BBK SSI intake along with the plenum spacer. All 3 align from the upper to lower intakes. Does anyone else have dyno experience with this intake?

I have to find a scanner before I can post the dyno chart, but I'll do my best to find one.

Is it common agreement that the heads are not my problem? Windsor Jr.s out-the-box would be capable of more than 300 HP?

put an offroad pipe on it , and post up the air/fuel numbers , and what is the timing set at ? what is initial and how much advance is that chip throwing at it ?

 

[Modular2v]

giving at 4650? what are the valve springs rated at? What did he have the full timing at when on the dyno? Something isnt right on the setup......why would you want to use nitrous to comprimise for something you should be making anyway? Im willing to bet its a valvetrain/timing issue!

 

[Dark Knight]

How do you know it's running out of airflow? Did you hook a vac. guage to the intake during the pull?

 

[Sicarius428]

I am not familiar with the SSI intake but I do remember somebody saying a while back that some of the angles are too tight and some of the cylinders can be starved due to one bank of cylinders getting most of the air. Not sure if it is true though. Is a 190 fuel pump enough? I would imageine you are verging on 255 territory with 400+ flywheel HP. Just another thought.
Kevin