450rwhp x2

XR7 Dave

Registered User
As many of you already know, this year at the SC Shootout Ira Robinson's car made 452rwhp and 479rwtq. This is not the most the car has made though, with 475rwhp being recorded a couple days earlier on a Mustang dyno here in town. This is on a bone stock rotating assembly:)eek:) with about 225,000 miles on the original rings with only a bearing replacement done about 15,000 miles ago. So what makes his car tick? Let's look at it and see.

We already know the pistons, rings, rods and crank are stock. The flywheel and balancer are also stock though a BHJ and/or aluminum flywheel would not hurt the combination any. The motor is in good condition and doesn't really use much if any oil (except for the leaks).

The cam I designed is mild enough to pass emmissions in any state but it does have some lope. Specs are somewhat proprietary but not really super secret. They can be duplicated by any engine builder who knows his stuff.

I ported the heads and they are not welded in any way but there are some significant tricks that are likely only to be discovered with time spent on a flow bench. I wouldn't expect just anyone to be able to get the flow #'s but a good shop should be able to. Exhaust flows over 200cfm but not as much as a Steig head. Valve seats are stock but valves are oversized. Nothing fancy but carefully worked over is the best way to describe them.

The intake manifold is stock other than more careful porting. The inlet is NOT enlarged in any way nor is the return adapter modfied other than for fitting the AR.

The AR is overdriven 17% and makes about 20psi through most of the rpm range. It is complemented with a MPFMIC, MP SC top, MP 85MM TB, and a custom 3.5" intake.

Other bolt ons include UD pulleys, RR's, 80MM MAF, and 60lb injectors.

The exhaust is simple with Kooks mid length headers, 2.5" downtubes, cats (yes you read that right), a 3.5" mid pipe, and 2.5" tail pipes/mufflers.

These numbers were made on pump gas with the help of a dual nozzle alcohol injection system to increase octane and lower air charge temps.

Just thought I'd put that out there.
 
thats amazing.....what size ar is he running?
i take it you did all the work on the heads......maybe i should keep you busy with another set;)
 
Dave,

I'm very impressed by the numbers that Ira's car is pulling. Since we have nearly the same setup I'm confused as to why his is making so much more power. Obviously the 5 speed is going to put more power to the wheels than an AOD with no lockup, but I didn't think there would be that much of a disparity.

David

PS: Glad to see my 1.7 AR is capable of supporting more power than I thought.
 
Dave,

I'm very impressed by the numbers that Ira's car is pulling. Since we have nearly the same setup I'm confused as to why his is making so much more power. Obviously the 5 speed is going to put more power to the wheels than an AOD with no lockup, but I didn't think there would be that much of a disparity.

David

PS: Glad to see my 1.7 AR is capable of supporting more power than I thought.


Its the Sneaky Pete NAWZ system he had in his glovebox that Ira admitted to us after racing was over!! :eek: LoL

J/K :D

The power that car made is unreal.. Ive always said these motors dont need any kind of shortblock work till well over 400rwhp.. Gives me hope for when the blue car goes down this winter for its conversion from "ehh its ok fast" to "damn this thing needs to be in pro V6 now!!"
 
Dave,

I'm very impressed by the numbers that Ira's car is pulling. Since we have nearly the same setup I'm confused as to why his is making so much more power. Obviously the 5 speed is going to put more power to the wheels than an AOD with no lockup, but I didn't think there would be that much of a disparity.

David

PS: Glad to see my 1.7 AR is capable of supporting more power than I thought.

David, often we overlook the little things looking for some big magical answer but in your case I would definitely start with your exhaust. It is woefully undersized. I also think that the dual nozzle alky kit has some value and the car could possibly make use of even more tuning.
 
I am happy for Ira but what amazes me is the large gap between engines power. Even Dave seems amazed at the diffrences between him and Ira. Besides my electrical grimlins what did I do wrong with my current setup?:confused:

Ken
 
David, what do you think 425-445 RWHP would = in a 5 speed?

550HP @ 14% drivetrain loss = 473
550HP @ 20% drivetrain loss = 440

Just a guess at losses. You probably have more than that, but Ira was on stock SC wheels with some aluminum in his drivetrain.
 
I can't emphasize combination enough. Ira's car made 260rwhp when Brian Herron put it together. That was after tuning by Jerry W, the AR, FMIC, cam, and Borla exhaust. Not numbers to get excited about by any means.

The first think we did with his car a couple years ago was diagnose some issues the car had - boost leaks being one of them. After fixing this the car made about 16 or so psi but the boost curve was lazy so I told him that he needed to improve the exhaust and increase the OD.

So Ira replaced the y-pipe and added 5% OD and after tuning the car responded with 345rwhp @ 21psi. Even at this point the car was very fast (12.76 @ 107mph) but the excessive boost was troubling me.

Ira decided to go with ported heads and so I told him right then he would also have to improve the exhaust even further and open up the intake as well. We made plans to do so.

I made several cam selections before settling on the one he finally has and the cylinder heads also went through several renditions before I was happy with them. In the end the car is running another 5% OD but making no more boost (20psi).

Some key points: The AR likes to run around 20psi. An Eaton, not so much so. They'll do it but there is a lot more heat involved.

In the case of Ira's car, we have always run a lot of boost. When it was only making 16psi it was a dog. We ran 20psi through the stock heads and we are running 20psi now.

Ken, your car has never made enough boost. Even back when I first tuned it I believe it was only making about 12-13psi on the stock motor. It was only when you first put the M112 on that it actually made respectable boost numbers. It's too bad it blew up because I think the car would have been totally different if it were properly tuned on the stock motor.

I'm also not trying to say anyone is to blame, but you've been chasing HP when you had mechanical issues with your EEC and/or ignition. It's too bad no one caught that earlier, it would have saved you a lot of time and frustration.

At this point I still believe that there is a whole lot of power waiting to get out but it's going to take some time to find it. My suggestion is to work things out until all issues have been totally resolved and then work at increasing boost until you have 19-20psi again.

And yes, I do believe that Ira's heads/cam package has a lot to do with his results.
 
Last edited:
David, what do you think 425-445 RWHP would = in a 5 speed?

550HP @ 14% drivetrain loss = 473
550HP @ 20% drivetrain loss = 440

Just a guess at losses. You probably have more than that, but Ira was on stock SC wheels with some aluminum in his drivetrain.

Ira's car doesn't have any aluminum driveline parts.

It's not so much that Ira's motor makes more power than David's, its more that David's has many advantages that don't seem to be worth anything HP wise - better heads, more cam, better ring seal, lighter rotating assembly...

But that can also be said for the other AR cars as well. None of them measured up to Ira's car either. But in each case you have a little bit of this and a little bit of that that's missing. Mike's car has too much cam....Brian's car had valve float, David's car doesn't have enough exhaust, etc.

Ira has everything I suggested to him on the car. He didn't tell me what he wanted, he let me do what I felt needed to be done. The only thing I would have done differently for HP reasons would have been an aluminum flywheel but for drag racing with 3.08 gears I felt that the stock flywheel would help the launches so I left that one out.
 
Mike Irving also has a similar set up. And he is on par with Neiberts car.
Do you think that you stumbled upon the perfect set up. And if replicated will it perform the same way.
 
3 or 4 years ago, I don't think we had enough knowledge on the motors and the tuning to feel comfortable pushing 20psi through the stock rotating assembly. People had tried before and broke things.

It's been through that kind of careful systematic work that has been done over the years that has allowed such a car to exist today.

It's great that you're finding this stuff out Dave.
 
Power is all in the heads and blower. With exception to supporting mods necessary everything else will be like pissin in the ocean to watch the level rise, more or less.

Thiiiss is why we neeeeeddd aftermarket heads.

I was also wondering why I wasn't making 450rwhp.
 
So....when are we going to be able to get these heads? I am trying to figure out what to do with my setup and hope I will be able to have it going back together by Christmas (still on track with last year:D).

Chris
 
Wow, that's some great power. So no mention of 1/4 mile time slips after the dyno? Should be able to toast off some low-mid 11's I would think making that kind of power.
 
Dave,

The treatment on Ira's heads is the same as the others you make or is this like a 'Type R' option? I want in.
 
Ira's car doesn't have any aluminum driveline parts.

It's not so much that Ira's motor makes more power than David's, its more that David's has many advantages that don't seem to be worth anything HP wise - better heads, more cam, better ring seal, lighter rotating assembly...

But that can also be said for the other AR cars as well. None of them measured up to Ira's car either. But in each case you have a little bit of this and a little bit of that that's missing. Mike's car has too much cam....Brian's car had valve float, David's car doesn't have enough exhaust, etc.

Ira has everything I suggested to him on the car. He didn't tell me what he wanted, he let me do what I felt needed to be done. The only thing I would have done differently for HP reasons would have been an aluminum flywheel but for drag racing with 3.08 gears I felt that the stock flywheel would help the launches so I left that one out.


Dave,

I've currently got Kooks mid length headers, 2.5" downtubes, cats removed, Magnaflow 2.5" dual inlet 3" single outlet...with a 3" center pipe back to dual 2.5" and Dynomax mufflers. I think it's pretty much the same as Ira has except he has a 3.5" center pipe w/cats and I have a 3" pipe w/o cats.

What would you suggest I change ?

David
 
Damn Sparky is this a sales pitch for your heads? Cause I want a set!

Actually I have a spare set now, what do you charge?
 
Now dont shoot me for saying this. Stock rings be it 130,000 or 255,000...Stock internals with only a bearing change. The reuse of the stock balancer. Sounds like a hand grenade waiting to go off. Any type of serious racing will surely put this motor to an end. Even if the stock rods could withstand that type of pressure the rod bolts surely wouldnt like it let alone the stock rings or pistons.

So basically what I'm curious about is why Ira would spend the money on heads a cam and misc other work and keep a stock over 100,00 mile bottom end in it (new bearings or not). Being Ira said do what you need to do. Why wouldnt you say dude...You need a bottom end that will hold up. Unless the reccomendation is to make 400 rwhp plus from stock unrebuilt bottom ends. Especially from an engine that is an unknown variable. Crud I thought it was out of a parted out 13X,XXX mile car.

I am not doubting the power it made..But I wouldnt risk useing a stock bottom end to make that kind of powerand risk ruining everything on top of it
 
Back
Top