Decat and exh.manifold. ? 2jzge. Performance.?

[herbiemercman]

My grandson has a Hyundai V6 sports coupe and he recently fitted a stainless steel free flow exhaust manifold and a decat pipe, we both noticed the difference in the performance but i imagine we are looking at only 10 to 15 bhp increase. The air intake was left as stock.

 

Have any members done this on their NA,and just leaving the air intake as stock, and is it worth doing? even if there is only a small increase in performance. herbie.

[That_Supra_Guy]

Is it a real difference in 'performance' or the new sound making it sound faster?

With the 3L being a fairly large displacement a little better flow certainly wont harm it, marginal gains though I'd say.

One things for sure though, a decatted NA is LOUD. But awesome loud so worth doing nonethless.

[herbiemercman]

Is it a real difference in 'performance' or the new sound making it sound faster?

With the 3L being a fairly large displacement a little better flow certainly wont harm it, marginal gains though I'd say.

One things for sure though, a decatted NA is LOUD. But awesome loud so worth doing nonethless.

 

Thanks for reply supra guy, never thought about the exhaust noise but i like the idea of more free flow. I may also have to consider small downstream cat to get through the mot test.? herbie.

[Style]

It depends what year your Supra is. Anything pre-96 (I think) just undergoes a standing emissions test and should be alright even when fully decatted.

 

Anything after that year and I think the emissions test/regualtions change and you're maybe looking at a cat or something like you mentioned

[Chris Wilson]

Manifold wise they make very little difference, some are built for LHD cars, so be very careful, they have issues clearing the steering column on RHD models. Most are pretty poor and may crack or blow. De cat wise you may see a few BHP more, and an increase in exhaust note. The N/A has a carefully matched intake / exhaust resonance associated with the variable plenum volume. Fiddling with manifolds, air filters and exhausts can screw this up, giving flat spots and a reduction in lower RPM torque. My advice, don't bother. Flog it and buy a TT whilst there are still a few nice ones left.

Edited May 22, 2015 by Chris Wilson (see edit history)

[Wez]

When I had an NA it came fitted with a Blitz Nur Spec, sounded really nice but quite loud, ended up fitting a stock exhaust back on and straight away it drove so much nicer lower down, more responsive and was also very quiet

[Nic]

When I use to manufacture NA exhaust manifolds I did a before and after dyno run, the car we tested was a bit down on power so the test wasn't conclusive but with the manifold fitted it made an 8hp increase. Not a huge increase in power but it did make the car feel more responsive and rev freer, it also made it sound a LOT louder.

[trebor69]

I've done this before, be prepared for a VERY noisy car that sets alarms off and drones.

[herbiemercman]

Many Thanks to all who responded, needless to say i am not touching the car, it has only done 50,000 miles from new and with the 5 speed box it is quite quick if you keep in the upper rev ranges.

 

Will settle down for a while now as i remember what chris wilson told me last year, it's a waste of time and can be problematic, chris sorted my brother's tt as no one else could sort it we had to take it to him on a trailer and leave it with him for a week, performance was superb when he had done his improvements. I may buy my brother's tt auto, it has only covered 43,000 miles from new, my only hesitation is i am not an auto man on a sports cars, may investigate the cost of a 6 speed manual conversion on it, have to sound my brother out on if he is ready to part with the car after his 21 years of ownership. herbie.

[Style]

Budget 4k all in for a 6 speed conversion, may be even more nowadays!

 

You could always buy the TT from your brother and swap the 5 speed box from your car as well. 5 speeds can handle BPU power so all you should need is a clutch on top of what you already have.

 

Then sell the NA as an auto with your brothers auto box

[herbiemercman]

Budget 4k all in for a 6 speed conversion, may be even more nowadays!

 

You could always buy the TT from your brother and swap the 5 speed box from your car as well. 5 speeds can handle BPU power so all you should need is a clutch on top of what you already have.

 

Then sell the NA as an auto with your brothers auto box

 

Thanks for the idea Style, also i did not realise the budget would be so high. Herbie.

[David P]

 

You could always buy the TT from your brother and swap the 5 speed box from your car as well. 5 speeds can handle BPU power so all you should need is a clutch on top of what you already have.

 

Then sell the NA as an auto with your brothers auto box

 

This can be done, details in the Transmission Group. http://www.mkivsupra.net/vbb/group.php?groupid=57

 

However, it'd be easier and financially preferable to use an N/A auto box and sell the T.T. unit.

[bignum]

You need a turbo to see any real performance from the car, have you looked at some of the aftermarket kits that some of the traders are doing:cool:

[Monkpower]

I had a stainless manifold, 2.5" decat into a 3" single box system (Whifbitz). The increased noise isn't for everyone but I absolutely loved it!!

Among other NAs it was very quick and a lot of fun.

 

There are some great NA turbo kits now which are definitely worth a look if you aren't considering selling up and buying a TT.

[David P]

I had a stainless manifold, 2.5" decat into a 3" single box system (Whifbitz). The increased noise isn't for everyone but I absolutely loved it!!

 

Maybe you should change your 'ditty' to "The Deaf Star"?

[herbiemercman]

Hi Guys once again thanks for your comments.

 

I drove my car to my local pub today as i do sort of twice a week, some of the younger guys are not familiar with the supra breed, when you step back and look at it this was a 90's masterpiece, the great white shark front end and then the awesome tail finn, my car is black and has "kahn" titanium alloys and has the commando toyota lower skirts, this car is 20 years old and still commands attention. When i drive off the pub car park because i have the manual gearbox and limited slip diff i can easily spin the rear wheels, can't do this with the autos, and i have the ferrari exhaust note at 3,000 rpm, somtimes you think, "grow up", i cannot imagine what 400 bhp would be like, my car is impresive at the stock 220 bhp, especially if you put the peddle to the floor. Over the last 20 years of ownership i can count on one hand the times i have been just about taken on the motorways, may be it is the superb aerodynamics, or the fact that the supra's reputation makes many people give up.? Also i have raced in the tt in the iom and i know many cannot read it at 100 mph pluss, the faster it goes the more it slows down for me, i am always looking for ways to go faster, but i am now asking why.? Herbie.

[Mike2JZ]

Hi Guys once again thanks for your comments.

 

I drove my car to my local pub today as i do sort of twice a week, some of the younger guys are not familiar with the supra breed, when you step back and look at it this was a 90's masterpiece, the great white shark front end and then the awesome tail finn, my car is black and has "kahn" titanium alloys and has the commando toyota lower skirts, this car is 20 years old and still commands attention. When i drive off the pub car park because i have the manual gearbox and limited slip diff i can easily spin the rear wheels, can't do this with the autos, and i have the ferrari exhaust note at 3,000 rpm, somtimes you think, "grow up", i cannot imagine what 400 bhp would be like, my car is impresive at the stock 220 bhp, especially if you put the peddle to the floor. Over the last 20 years of ownership i can count on one hand the times i have been just about taken on the motorways, may be it is the superb aerodynamics, or the fact that the supra's reputation makes many people give up.? Also i have raced in the tt in the iom and i know many cannot read it at 100 mph pluss, the faster it goes the more it slows down for me, i am always looking for ways to go faster, but i am now asking why.? Herbie.

 

Cool story

[herbiemercman]

Cool story

 

Thanks Mike. Herbie.