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steveos89xr7
04-14-2011, 06:48 PM
hey guys, im new to this site but i thought it would be a good place to get info on my car. i just recently bought a 10% overdrive pulley for my 89 xr7 and i was wondering what size belt works with that pulley? i was also wondering what would be a good gearset for my car? 3.27 or 3.55? im planning on just a mild street car with some strip time. are 3.55's really that aggressive? Info would be appreciated:)

shoalcracker
04-14-2011, 07:07 PM
39" for the belt.

Paul

rzimmerl
04-14-2011, 07:48 PM
Need the transmission type to suggest a gear ratio.

steveos89xr7
04-14-2011, 07:55 PM
sorry, its the 5spd

the-big-e
04-14-2011, 08:08 PM
Either one will work.....

Most 5 speed guys seem to like the 3.27s.....:D

3.55s make for a very short 1st gear.....:p

steveos89xr7
04-14-2011, 08:13 PM
do u know what my revs would be at 70mph w 3.55's?

hawgy
04-14-2011, 11:55 PM
if you're going to have some hwy use go with the 3.27 the gears in the tranny are very low already. with 3.55 at 70 i would say around 2600-2800?

90blkbrd
04-15-2011, 08:46 AM
hey guys, im new to this site but i thought it would be a good place to get info on my car. i just recently bought a 10% overdrive pulley for my 89 xr7 and i was wondering what size belt works with that pulley? i was also wondering what would be a good gearset for my car? 3.27 or 3.55? im planning on just a mild street car with some strip time. are 3.55's really that aggressive? Info would be appreciated:)

2.73's...leave them alone. Spend the money on performance parts like heads and a cam and make more power.

The exhaust is very restrictive on your car. The very first performance modification is removing the resonator and the pinch point right behind that, as they cause a lot of back pressure. The resonator is the muffler right after the cats.

Oh and a 10% supercharger pulley is to much for your stock blower. 5% is the most you should run on a unported 89-93 supercharger. If you still decide to run it you need to do some intercooler upgrades such as adding a fan, double intercooler, Magnum Powers FMIC or a custom front mount. If you don't you'll find the car has more pep to about 30 mph and then lays on its face due to high inlet temperatures and the EEC pulling timing trying to save your motor.

steveos89xr7
04-15-2011, 03:36 PM
thx for the info man, ill work on the exhaust. im ordering meth injection, so that will solve the spark retard issue

90blkbrd
04-15-2011, 03:55 PM
thx for the info man, ill work on the exhaust. im ordering meth injection, so that will solve the spark retard issue

It will help. I wouldn't go as far as saying it will solve it.

90coug
04-15-2011, 04:41 PM
Like stated before, open up the exhaust! Or the head gaskets gremlins will more than likely pay a visit.

rzimmerl
04-15-2011, 04:51 PM
The alky kit will help, but at this point you would have better overall performance going to just a double intercooler from Ken.

steveos89xr7
04-18-2011, 04:16 PM
are the intercoolers really that inefficient on these cars? what is a good spark plug for these cars?

AJMgearhead
04-18-2011, 04:23 PM
are the intercoolers really that inefficient on these cars? what is a good spark plug for these cars?

Autolite 103 Copper Core. I gapped mine at .035

http://www.summitracing.com/parts/FRM-103/
Summit had the best price when I bought mine

steveos89xr7
04-18-2011, 04:59 PM
thx for the info!

AJMgearhead
04-18-2011, 08:04 PM
You got it. I'm putting the 5-10% pulley on my SC soon as well. And tomorrow the mufflers come off :cool:

hawgy
04-18-2011, 11:12 PM
Autolite 103 Copper Core. I gapped mine at .035

http://www.summitracing.com/parts/FRM-103/
Summit had the best price when I bought mine

just got my 103's at rock auto had them for $1.08 so i got 2 set's

stangerbanger
04-19-2011, 08:57 AM
i dont know if the gearing is different in a mustang T-5 compared to a tbird mrwhatever but i got a 4.10 gear and its crazy lol. but i do spin the motor 3 grand at 70ish

AJMgearhead
04-19-2011, 09:07 AM
just got my 103's at rock auto had them for $1.08 so i got 2 set's

Even better!