I intended to post this Thursday night but I figured I would put out a little teaser.
My car is going on the dyno Thursday for it's tune with the new setup. I'm geeked! I've been running a base tune that they put in last fall. Car feels very good/strong.
Here's a few pics.




GMHTP had a 383 with ported stock heads put down (uncorrected) 448.5 at the crank. I have AFR190 street port. Not sure if this is better or worse than the ported stocks. Find out Thursday. My hope when I started this was 400 HP at the wheels. Wish me luck.

Steve

Very nice, that's almost too pretty to hide under the hood. Let us know how it goes.

Good luck!

That's about what I'm looking for in my build. Let us know how it goes!

that is a beautiful motor - is it from golen?

Thanks and no, it was done at a local shop in Utica, Mi.

sweet ive been waiting for you to post numbers. im interested in how it does. i think youll do fine and don't forget overall numbers arent as important as area under the curve.

Well here we go.
The final numbers are in, 370.6RWHP (5900RPM) and 361.2 torque(4600RPM)
The dyno was reducing by .95% for weather. Making uncorrected 388RWHP,378T.
One thing that was not right was a quick drop in HP at 5900 RPM. At 5900 rpm there was 370HP, at 6300 rpm 330HP. A drop of 10 HP every 100 rpm. He was slightly concerned with this. Due to this we were lifting at or right after 5900 RPM. I was very cool with that. I did not want to watch my motor let go on a dyno.
The dominent theory was valve springs. The springs came with the AFR heads. I need to find out what they are. I hope AFR can tell me. Cam specs say to use Comp Cam #26918-16

When the wife gets home and tells me how to get the scanner to work, I will post a graph.

383cid
AFR 190 street port
10.5:1 compression (approx.)
Diamond pistons
Eagle rods
Comp Cam: @ .050 224/230/112 w/1:6 rockers,.503/.510 lift (not very big at all)
1:6 pro magnum roller rockers
electric W/P
Alum flywheel
6spd
11x17/315's

A little short of my goal. And I am a little disappointed. But not completey. For now it is what it is.
Now to have fun.

Steve

how does it idle and drive? should do very well with that. the package holds more potential for sure. yes that cam is very small for a 383, but after what you did a cam change isnt too hard. so heck yeah get out there and smoke some tires

Are those lift number you give, the lift with the 1.6 rockers? If so that is really low lift. If that is the COMP Extreme cam I am pretty sure that with 1.6 rockers you are really getting .535/.544 lift. The larger displacement engines can really swallow a much larger cam without the engine becoming too radical.

What was your Air Fuel Ratio like? What tune do you have in the car? If you are still running a stock tune the you will really be leaving alot of hp on the table.

Sorry you had disappointing results, Steve.

First things first, get those valve springs replaced with something decent before you bust one or hurt something else. The springs that come on those heads may be OK for a small flat tappet cam, but they're seriously overmatched with an XE roller. The 918's will work exceedingly well for you but they aren't the only choice.

I knew you wouldn't set the world on fire with huge HP numbers with that cam and those heads (although that may improve some when you can rev it a little higher), but you said you were looking for a torque monster. That's what concernes me--where's the torque?

Of course until we know more about the A/F ratio, knock retard, etc, the tune is something to suspect.

But since your shop did so many other things wrong, I wonder how much faith I'd have in that 10.5:1 compression ratio number. How big were the chambers on the heads? Deck height? Piston reliefs? Head gasket thickness? I'm wondering if the shop didn't slap it together like they do all other street SBC's with a 9:1 or so. Something's not right with that torque number--and that's long before the valve float comes into serious play.

I too noticed the low torque. Just for comparison, my first 396 (years ago) with my hand port LT-4 heads, GM Hot cam, 1-5/8" shorty header through a restrictive exhaust, and a bone stock tune only made 363 rwhp but was still in the upper 390's rwt. I too had HP drop off problems at high rpm. I later switched to the Comp XE 244/234-114 and long tube headers and even with a stock tune I jumped to 385 rwhp and about 400 rwt. Then with a tune (not even using a wide band O2) it went to 403rwhp and 412 rwt.

I put down simlar numbers in my car, but with a stock bottom end... 366rwhp / 351rwtq. Hopefully with a bit of evaluation you'll be able to figure out where the additional power went.

http://web.ics.purdue.edu/~promba/albums/Z...un_01092004.jpg

Can you list the rest of the set-up?

Here's the graph.
I had a guy at work who is a big drag guy and engine man show me how to read the cam card. With the 1:6 rockers the lift is actually .536/.544.
Check my math.
Lobe lift .335/.340 (from cam card).

Steve

Mustang Dynos ALWAYS dyno lower than Dynojet dynos.

You very well may be approaching 400rwhp ... on a Dynojet ...

This is exactly what the dyno guys told me. They said they have done tests on both machines and have seen as much as 30 HP swings. So I asked him, "which one was correct". He started into some shpeel about neither dyno being wrong. In my eyes there can only be one correct answer as to how much HP a motor is making.

I don't remember the numbers, but he told me I was above any stock C5 Z06 they have tested. Especially in the torque. That's nice to know.

I'm not really to worried about the numbers. The cars plenty fast for me right now. I am going to look into the springs though, just for piece of mind.

Steve

I tend to agree with you. HP = (Tq*RPM)/5252. Well, Tq is measured in Ft. Lbs. so I'd have to say that there's not a whole hell of a lot of leeway for accuracy for the exact HP #'s. However, I do know that the dynojet is an inertial roller dyno and the mustang is an eddy current dyno. I guess the real question is, "which machine measures rwtq more accurately?

That makes me feel better. If you want numbers to compare to everybody else, go to a Dynojet. They're the same every time--that wheel's mass doesn't change. With a Mustang dyno, god knows how the guy running the thing ran the thing so your results depend upon what he was doing.

Nice flat torque curve but a big drop in the upper RPM range. Two things, like Jon said, change the springs and check your fuel pressure. Did you change fuel pump or injectors?

I just got two books:
How to Rebuild Small-Block Chevy Lt-1/Lt-4 Engines: Step-By-Step Rebuild to Factory Specifications
and
John Lingenfelter on Modifying Small-Block Chevy Engines: High Performance Engine Building and Tuning for Street and Racing

Really good books on the small block engines and lots of insight and experience from Lingenfelter himself.

Aah yes, the Mustang Dyno. I figured your numbers were from a DynoJet. I would say that your motor is in fact a pretty strong runner.

AFAIK, not all Dynojets have the same drum mass. Some jets have 1 drum, some have 2... it all depends on what model it is.

Correct, there are some models with different drums.

Concidering all the experience that you all have I feel better after hearing that you guys feel better. The car does run very well. A little rough when cold but otherwise fine. The cam may be costing me some top end HP but the throttle response is incredable and the low end torque is one thing I was looking for.
As far as the flat torque curve. The early runs weren't so flat. The begining of the curve did not look anywere near this good, It arched in from the bottom of the graph. He then did some things with the Lower RPM air/fuel and it brought it to life.

Steve

As others have said, you might want to look into another cam. You would be surprised how tame even a big cam like GM 847 (234/242 112 LSA 0.575"/0.595" w/1.6 rockers, if I remember correctly) behaves with a 6-speed car in a 383ci engine (when it is tuned right). Good luck.

Tony

For those interested, I looked it up. All the various model 248's (by far the most common) have two 48" rollers. Only the much smaller 224's have two 24" rollers. And of course the very few model 424's you hear about for those rally cars. They have four 24" rollers.

Man, I am so quick. I only stared at those specs for quite some time before it dawned on me what the model numbers stand for.

Now you'll all know, just by the model number.

http://www.airflowresearch.com/

I just looked at AFR's web-site and noticed there recommendation on valve springs. Click on the LT1/LT4 link to the left, then click on the 195's. These are 195 heads and mine are a discontinued 190 model but I'm sure the theory still apply's. They mention upgrading springs when running hydraulic roller. I am going to have to get this done.

I emailed the head manufacture AFR yesterday. I described my basic setup to him and asked what springs he would recommend. This is his response. Anyone have any experience with the hydra-rev kit?

Hi Steve

Rather than do a spring change you would be better off using our Hydra Rev kit, it will allow you to go up to 7000 rpm before you start getting into
vavle float. AFR is no longer doing updates to competition porting, but the 190cc heads you currently have on your 383 are capable of up to 500hp
if you stay out of vavle float. You still have plenty of cylinder head with out any additional porting for your application.

Scott Sperling
AFR Sales/Tech(
818) 890-0616 X102


Any thoughts?

Steve

at this point i see the hydrarev kit as a bandaid instead of a solution. id change the springs out first then if your really gonna beat on it up to max rpms id look into the rev kit. those are my thoughts and how id do it personally.

I Agree. All I see myself doing right now is changing the springs.

Screw AFR. A rev kit certainly isn't a bad idea, but you need to get those springs off the car!

Steve, guess I missed this thread until now. If you remember, I also ran the 224/230/112 XE cam last year in my 350. I was using 1.65 rockers however. I got 340 RWHP at about 5800 rpm on a Mustang dyno here in town. At the time I was using the 612 springs from Combination Motorsports. They were surprisingly cheap with retainers and locks and worked great.

If you plan on upping the cam later I'd go with better springs, but for the XE 224/230 the 612 springs are well within their range.