1986 928 Acceleration Question
 

After recent upgrades my 928 is running better than ever. But it is a 5 liter and my friends late 80's 5 liter mustang will do circles off the line around this thing. I replaced the plugs, wires, cap, rotor, temp 2, injectors, TIMING BELT & W.P., rebuilt MAF, checked adjustment on throttle and Bowden cables, checked/found/repaired vacuum leaks, cats are clear, new O2(not univ.). The only thing left I can think of is the actual cam timing. Or maybe there is nothing wrong with it as I have never driven another one.

Porkens chips will free up a few ponies. Also these cars are not known for their off the line speed.

If you want better off line, hook up a manual kick down switch, 87 FPR and kens chips.

My 85 will do 6.5sec 0-60 if I really push it. But that's about all you can get from an S3 auto until you drop in a supercharger.

Or that's all I seem to get. :)

Hi-Flo cats and an X-pipe will do wonders alone. Unfortunately, given the 5 liter V8 is such a big powerful engine that should be putting out much more power, I believe it's limited because of the fat organ style intake. Your friend's Mustang may beat you off the line but won't get much far after that. The 928 excels at higher, less legal, speeds.

Adamant,

Only? That's about stock. I was doing 6.5 repeatedly before x-pipe and new O2 sensor with my 86. Should be able to do 6 flat or low 6s with. I anticipate to squeak into the 5s with Ken's latest chips and the Ford injectors.

Very tall gearing.

Both cars have 5 liter engines, but your car certainly has taller gearing (and a much higher top speed). What is the weight difference between your 928 and his Fox body Mustang?

Your car is setup for high speed travel, not acceleration.
You could run circles around him on a long high speed highway trip.
I have have had a 5.0 Mustang for 26 years.

Ya know, I need to get out and give it a few more runs. The only thing I have not done is the injectors. :)

Run a can of BG 44k in the fuel then drop the oil once you've gone through a full tank. Really woke her up for me when I did it. Apparently I had a bunch of crap inside that engine because the oil was fairly dirty after the run.

Of course that's only a small patch to having your injectors professionally cleaned or switching to the 4-pintle style with better atomization.

44K is good stuff. I've been using it for nearly 20 years.

WOW great responses!
 

Thanks for all the replies. Now I must admit, please don't tell Ken, I forgot to mention I did the Porken chips as well in my mods. Along with a custom cat-back magnaflow 2.5" exhaust, it sounds great! The things I have not tried are the high-flow cats or x-pipe. That sounds like an idea. I would like to find out more info and installation suggestions on this manual kickdown switch I heard about. I understand the idea of it and see 3 major ways to do it, one including a valvebody replacement. I agree with 44k, I sell a lot of BG at my shop. However I did install the Ford style (4hole) injectors. Out of all the mods I did I would say the chipset, injectors and free flow exhaust woke it up the most. I did send the MAF to injectionlabs in Boulder, they do a great job. along with the 87 FPR I found from Napa. Works great. I understand that the gearing is high and that is a great point. Has antone ever done a rear gear swap? parts? did they live to tell the story?

That's really sad.

My 85 euro auto (2.54) toyed with an early 00's Mustang GT with 5.4sec 0-60, beat him easily up to 70 and then left it in the dust. I ordered a Mustang GT from the factory in 86, great car at the time for the money, but no mustang was a match for the 928 I own in any category, not even close. It's laughable.

Do you sell Bg 109 too? I'm trying to figure out how to do a simple quick BG treatment on my car aside the 44K. I think 109 or QuickClean in the oil, drive it for 15-20mims then drop the oil.

EDIT:

I would also check timing too for optimized performance. Pretty sure if your off with the chips you won't get the best results. Also get the xpipe and hi-flows. You have no idea how much of an effect it has on the car. It's night and day.

Yes I do sell a lot of 109. I like it for severe sludge in the engine. For regular oil and crankcase maintenance I live by MOA.

I am concerned about my cam timing. When I replaced the timing belt it appeared that the right bank cam gear would not line up exactly on the mark when tensioned. It's like a half tooth off. So I went to the half tooth advanced on the cam. This is before I learned of Porken's 32V'R tool to reset the cam timing. Any thoughts?

I think you want to be dead on Driver side and 2 degrees retard on passenger. Or the other way around. Can't remember but it's 0 and 2 some way.

How much is 109? Trying to locate it here. Do you happen to ship?

It runs around 12 bucks. I would ship you some no problem. just private message me your address.

look into borrowing a 32V'r. if you can't find one locally let me know. I can lend you mine, if you want to cover shipping. it will fit in one of the small flat rate boxes, so I shipping to you would be about $6.

Awesome. Thanks.

Just going to check the local Honda dealership to see if they got any. I can find 44k and MOA just about anywhere except the others.

There's a ton of great people on Rennlist that can lend the tools for the job. Borrowed a 32vR and bump stick from Steve here.

Try to borrow the bump stick also. Makes rotating the gear and timing so much easier.

wow Simon! that's incredibly nice of you! I will take you up on that offer. Let me check when I can do it and ill work out the details.