Hey 12.90's was too easy-lol,Converter lockup worthwhile?

richy rich

Richy Rich
Apr 11, 2003
Hey guys,I got a stock 87 GN,mods include,bigger fuel pump,hot wired,adj. reg,cold air,Test Pipe,& turbo tweak chip.W drag radials & about 19-20 lbs of boost[c16 mixed w pump 94]It ran a 12.90 at 102mph.1.71 60ft.That about the normal "reciepe" for a 12 sec car?Low MPH though?Either valve springs,or does locking the converter up help a bunch?I was told about 1mph.Man thats a quick little car for not much work,I was real happy with how it ran!I always thought the easy 12sec parts list was BS-Guess not!LOL
Ive seen as much as 3 tenths and 4 mph locking the convertor I cant say you'll gain that much but it cant hurt. just remember when u lock it you have to manually shift 2-3 as its shifts its self at about 4800 when locked up.
So leave in 2nd gear when you launch and shift it.
If the springs are over 40-50k they are toast, they will help at least 1mph up top.

What rpm is it shifting at?

If you can remember what rpm you went through the traps at you can figure out your converter efficiency unlocked. I'd bet your over 10% so locking it will give you back at least 2mph. At your power range locking the stocker isn't a big deal on clutch wear IMO and worth doing.

I'd look into Meth injection and then up the timing, the stock turbo can only push so much and timing is an easy way to get it moving and make use of the octane you are mixing at.
Well for starters,Yes a Razor kit is on order as we speak.My question is,will the Razor kit give me more power at a given boost/say 19-20lbs,then a 94/c16 mix?Given no knock retard with either set up?I can only run about 13lbs boost on pump gas?Not sure why only that much?Throw some octane[& another 5lbs boost] into the mix & the car is Jeckyl & Hide!!Power is what 15HP for every lbs of boost?As far as the Springs go,I got a hi Milage car,What should I swap in?I have a "reworked" D5 Converter.I can hold 11lbs boost on the starting line like nothing,2600prm,before it builds boost,I really like that set up!Not a bad 60ft for a stock car eh?LOL
The D-5 converter, even if its been reworked, still has a large diameter and alot of rotating mass. Simply dropping way down in diameter, even while keeping a low stall speed, can do a great deal for acceleration...ALOT more than you may think.
Or, get a chip that will do it for you.

I'm not a fan of the stock converter and reworking it is a bigger mess IMO due to losing top end efficiency by altering the stator fins. You'd have to lock it IMO at the track so you can gain back that top end loss for sure.

Alky is better at running more boost than adding timing IMO. What I'd do at the track is keep your octane mix at 50/50 94/116 ( about 105 ) and run around 25 degrees of timing ( safe on this octane mix with our compression and the psi below ). With Meth injection you can easily run about 22psi to 23psi with 94 octane let alone a 105 mix so you're in for a surprise when you install that alky kit. Meth and 105 octane with 25 degrees and 24psi is very practical with your setup without an aftermarket intercooler. Tune around 11.5 with Zero knock and you're golden.

The issue with the stock turbo is backpressure, the more you free up the better it can breath and not puke out tons of hot air. 24psi on a totally stock inlet system is different than 24psi on a totally freed up inlet system.

Wanna help it breath and get more psi with Alky.

9" K&N Cone
Z06 Maf
3-4" Inlet Pipe or FTS 4" Mafless Pipe
Aftermarket Intercooler
70mm Throttle Body and Plenum

These are all things you can do with the motor in the car and free up precious backpressure to help the turbo's compressor map get back to the fat island.

BTW, an old coil pack trying to fire at high psi can start blowing out the spark and plugs need to be around .032 with alky.
In addition to the spark blowout comment- Your coil packs and entire ignition are only as good as the grounds in the whole system. Supra guys often run an extra ground strap to cure a whole host of electrical problems that come with time. With a 20 year old plus wiring harness, the problems are much worse. I made an extra ground strap for mine, with an 8 gauge cable and copper lugs soldered at each end. I grounded the ignition module frame to the inner fender and it did seem to help. I could run a .045" gap at 23psi with no problems. And this is with a 100 dollar autozone ignition module. No spark blowout. Cleaning out the fan relay contacts makes a huge difference in the speed of the fan and load on the whole system....so of course it'll make a difference with the ignition system. Good grounds are paramount with any electrical system. Using copper anti-seize (not aluminum) on the spark plug threads can increase electrical and thermal conductivity...so stronger spark, and more heat transfer from the plugs to the heads. Theres alot of little things people overlook.
Fwiw, I have a stock long block, turbo, intercooler and with new springs, 36# inj, red's xp pump, TT chip, razors alky, a cone filter, 2800 stall 12" TC and a gutted cat I went 106 mph or so with the TC locked. This was at slow fontana on 21.5# of boost and 26* of timing with methanol. no knock at all and only tuned with a Scanmaster. I'm sure people have gone faster with less but I bet with some slight tuning and tweaks you've got more in it.

Back in 2000 when my car was fairly stock, I ran 14.09 @ 99 at 15 psi with the converter locked. It works for me. -Jimmy
If you want to get more power to the ground...not waste power, get a small diameter TC with little slip. Usually the smaller ones dont have lockup, but there are some that couple pretty close to 1:1. Its an expensive investment, but worth every penny. You'll be shocked at the massive improvement in acceleration. Couple that with an aluminum driveshaft, thats close to stock diameter, and you'll free up even more wasted power. I had an art carr 16930 non lockup, and when I switched to a stock D-5, it felt like it lost 100hp...I always say that every time I mention it, but its true. Get something of the same diameter (9.5"), but with lockup if you can afford it, and theres no reason you couldnt drop a second or close to a second of your ET over a D-5. Over inflate your front tires or get some skinnies, pull the front sway bar to get more lift on launch, do an ebrake/brake launch...you could drop 3-4 tenths off from that alone. You could probably cut 1.5 seconds off your ET without even touching the motor, between a small diameter TC with a flash stall about 200rpm above where your boost peaks, and those other things.
Anyone ever see any improvement from headlight covers? Those big headlight pockets seem like they'd cause alot of drag. 96-98 mustang owners typically see a 1-2mph gain by just removing the wing, so it seems possible.