i blew my engine 2 months ago .. and my uncle rebuilt my engine .. i only put 1500 miles on tha new engine.. and somehow it only goes to a top speed of 115mph .. and my 5th gear always grinds when i put it to 5th .. wha could be tha problem ? and how to resolve it ?

 

probably the 5th gear syncro is gone and you will have to replace it.

 

Do you have 10" wheels?

 

See if the throttle plates are opening all the way, a 3 fd with a blown apex seal will go that fast .How high will it rev in the lower gears , how much boost do you get??

 

Where did you get the engine from Japanese rx7's are limited to 115 mph, Did you dad do anything with the ecu ??? if so there is one wire on the ecu that needs to be cut to deristrict it. Don't what one

 

Where did you get the engine from Japanese rx7's are limited to 115 mph, Did you dad do anything with the ecu ??? if so there is one wire on the ecu that needs to be cut to deristrict it. Don't what one I don't remember
regards

Brian

 

115mph is only 4600rpm in 5th gear with stock rims. Unless your ecu is screwed, you got major problems...

Can you rev past 4600rpm in lower gears?
what boost are you running?

 

You're probably not making full boost, or have a clogged cat or something.

 

That's what you get for having your uncle build your engine ...sorry to make fun in a time of crisis but I had to...
Probably should check
- compression
- boost
- plugs

 

the middle of 4th gear should run you to 115

 

Yeah I got it up to 120 on the freeway and kept it under 4,000 RPM's. It's great I love this car.

 

maybe there is something wrong with your secondary turbo. Is it kicking in/boosting? Check everything. I'm not the one to give advice but I would say ask someone else about that.

 

maybe there is something wrong with your secondary turbo. Is it kicking in/boosting? Check everything. I'm not the one to give advice but I would have to say ask someone else about that.

 

oops, sorry about that. My comp messed up!

 

Check and make sure you did not pop off a vacume hose or two.

 

I think you have a bigger problem than a loose vacuum line or bad turbos. A car with the aerodynamics of the FD would only require about 100 hp to go 115 mph. You either have some sort of ecu issue or your engine is hosed.

 

......