GregBBRD

Just finished a 6.5 liter stroker '85 engine that the customer decided that he wanted to retain the original heads and intake system. His desires were to have the engine be extremely reliable, wanted it to make 325 rear wheel horsepower, and wanted it to look original. We used our usual proven Moldex, Carrillo, J&E, Nicosil cylinder approach. We had to design a new piston for the larger '85/'86 combustion chamber (that doesn't have the quench area that the later heads have).

Since we had never built a stroker using these heads and intake system, I approached this project carefully and kept my expectations to a minimum. We used custom larger intake and exhaust valves and had the cams "tweaked" a bit....without welding on them....which the customer desired to avoid. Since we had the valves made, we could reduce the base circle on the camshaft a bit and just make the stems of the valves longer to compensate. We did not modify the location of the lobes, so the 112 degree lobe centers of the '85/'86 engine were retained. All we did was to "improve the area under the curve" a bit. Since the customer wanted reliability and not the ultimate horsepower machine, we kept the compression and the other pieces very, very mild. Think street engine that could pass California smog.

We "borrowed" (with his blessing) Louis's idea of using a spacer to move the pan away from the crank and we built a completely new version of windage trays....in an effort to solve one of the 928s oiling problems. Seems that all of the engines that are used on the race track "puke" copious quantities of oil out of the breathers in the valve covers...especially the ones on the 1-4 side of the engine. The pan spacer and windage trays completely solved this issue! We took the car out to Fontana with less than an hour on it (which means that the rings are not seated, yet) and narry a drop of oil came out of the breathers! We vented the valve covers to a breather assembly and caught the oil that was forced to the breathers from the bottom of the assembly....which made sure that we could monitor the amount of oil that came out of the valve covers. And if you've ever seen the banking and the "g" forces that are generated at Fontana, this was a major accomplishment to eliminate the oil "gushing" out of the valve cover breathers!

We tested the results at Fontana and the engine seemed fairly strong and ran very smooth. Since we were in a hurry, we didn't have time to dyno the car and check the output. We simply broke it in on my eddy-current Mustang dyno, which we use for break-in and setting mixture, since we can hold the car virtually forever at any given load and rpm with this style dyno.

Finally, we had the time to take it over to the local "dynojet" guy....which we do so that we can compare results with everyone else's results....after the engine ran the weekend at Fontana.

Here's the big surprise. The engine made 386 hp at the rear wheels. The torque was very impressive. The engine made over 400 ft lbs. from 3,000 to 5100. This compares very closely with the race engines we have built that used late heads and intake systems, but with a broader torque range!

Guess we need to quit looking at the '85/'86 engines like they are just the "early" 32 valve engines that never really worked! There's a whole bunch of potential in those engines that gets ignored and laughed at by the guys with the later cars!

gb

928ntslow

Greg, that IS impressive. I think it is a fine outcome from an odd request. I say this because it sounds like the owner has no intention on doing anything but driving the car and having a bit more power at the on ramp. Most would figure that if you are going to modify an engine (and to 6.5L at that), you would simply "go for it" since you are already in there and shelling out the cash.

If you lowered the profile of the exhaust cam and installed longer stemmed valves, would you have made for a longer duration? Was there any porting of the heads? Lastly what was the "custom" Intake...CF?

Nice solution to the oil consumption..how easily can this be adapted to a GTS?

John Veninger

Will you be selling the windage trays?

Rick Carter

I'd like to know more about the pan spacer and windage tray; pics?

SwayBar

He used the stock intake:
It was the intake and exhaust valves which were custom:
Looking forward to seeing the dyno chart!

tv

Keeping the stock look but giving it that level of power is awesome. Sounds like gregs idea for the 4.7 euro engine. Would "group buy's" in the future bring costs down on a project like this?

Mike Frye

HOLY CRAP!

Stock intake, stock appearance, over 100hp gain (I think stock is 288 at the crank). Yikes.

Imo000

Very impressive!

Shane

Thanks Greg for proving something I always suspected...

Imo000

Actually over 150hp from stock and over 50% more than a stock engine.

Jim bailey - 928 International

So Greg you screwed up ..."wanted it to make 325 rear wheel horsepower, and wanted it to look original. " You made 386 RWHP ! you went 60 hp OVER ! Don't you just hate it when that happens ... But I would expect no less from the very best engine builder I know. No hype no BS just proven results. Now about that old very brown 1980 with 198 RWHP

BC

+1

Also, how much was taken from the base circles, and I assume lash caps were used?

SwayBar

BC

You have a serious attitude problem. I will not defend my post in any way, but I will say that many times you are either totally unhelpful here or downright rude. You're job here is not question cop, and your most recent post to 918 when he was asking for NEW info, was also unhelpful.
Go bears.

SwayBar

A little sensitive today Brendan? I answered your question for you, and I'm sorry if I didn't have the time to put smiley faces in my response if that is what you require. I believe you are the one with an attitude here.

As for 918, how many times has that been discussed? Doing a search will reward him with a wealth of information.

Second-best team in the NFL.