BPU and APU

[Fulcrum2000]

Hi All

 

As someone who owns a stock TT Supe I know there's been various forums about going BPU and APU but none of them actually mention the 'real world effects' of both and I'm sure all of us stockers need this info before making any upgrade choices. So with this in mind, and moving away from quarter times I have a couple of quezzies for those who have took the plunge:

 

1) We know Supes are about 5 secs/60 stock, what 0.60 do you get from say a 450hp decent BPU and a 550 Single APU

2) I assume when the science kicks in the top end will be less affected but assuming a stock has somewhere around 170mph what effect on the top end would a 450 BPU and a 550 Single APU have.

 

The point is we love our Supes because they thrill us and we like to blat them now and again to balance the costs of owning and adoring them, but I'm not into telling everyone my HP, I just want to feel the Gs. Any info would be appreciated.

[Karl M N]

I've got a bpu uk spec and I had someone time me with a stop watch at 4.5 seconds. Never put the car on a rolling road so I couldn't say for sure what the power is. This was at 1.2 bar, I don't know if 1.4-5 would make much of a difference.

 

Also bpu's seem to be closer to the 400bhp mark than 450.

 

With some decent tyres you will definelty feel the difference though. Bpu is great value for money as well considering how cheap it is.

Edited May 14, 2017 by Karl M N (see edit history)

[mellonman]

Bpu can be done for under a grand and single cost between 5 and 10 , I loved my supra when it was bpu but now im single its not so responsive but im limited by the auto box only being able to hold around 500 bhp and ftlb so cant even turn my boost up. If I was doing it all over again I would just stay bpu, cheap easy with great gains .

Single is great fun but less driveable as a daily

 

That being said if I was manual 6 speed then small single is worth it even then traction is a issue and I honistly think 600 -700 is the golden zone

[Fulcrum2000]

Cheers Mellonman but what times are you getting on that set up?

[Dnk]

Aren't times somewhat pointless unless your seriously drag racing the car ?

 

Never once timed my cars on the rd, its how they drive overall that counts, top end is pretty pointless too, on most circuits you wont reach the

top end and if your on the road the punishment these days is simply too high.

 

A good bpu car at 1.25 bar should be making 400 hp, pushing the bar higher will just shorten your turbos life for very little gain

[Mk4Gaz]

Bpu can be done for under a grand and single cost between 5 and 10 , I loved my supra when it was bpu but now im single its not so responsive but im limited by the auto box only being able to hold around 500 bhp and ftlb so cant even turn my boost up. If I was doing it all over again I would just stay bpu, cheap easy with great gains .

Single is great fun but less driveable as a daily

 

That being said if I was manual 6 speed then small single is worth it even then traction is a issue and I honistly think 600 -700 is the golden zone

Bang on

 

 

[mellonman]

Cheers Mellonman but what times are you getting on that set up?

 

Idont know as I dont have the correct timing equipment to give a factual answer , but I would say 0-60 on a single turbo would be less then a sqenctial bpu

Have a look here for the drag times for idea

http://www.mkivsupra.net/vbb/showthread.php?166336-Supra-Drag-Racing-Times

[tooquicktostop]

I have owned all formats of Supra from BPU, Small Single both with Auto and 6 Speed and I would say without any doubt BPU Auto was the best driving and most reliable and would be my go to set up if I ever did it again

[Marcus GTE]

I have owned all formats of Supra from BPU, Small Single both with Auto and 6 Speed and I would say without any doubt BPU Auto was the best driving and most reliable and would be my go to set up if I ever did it again

 

[Frank Bullitt]

I have owned all formats of Supra from BPU, Small Single both with Auto and 6 Speed and I would say without any doubt BPU Auto was the best driving and most reliable and would be my go to set up if I ever did it again

 

Would you just go basic BPU or everything possible at the BPU level whilst keeping the sequential system?

[Guigsy]

I have owned all formats of Supra from BPU, Small Single both with Auto and 6 Speed and I would say without any doubt BPU Auto was the best driving and most reliable and would be my go to set up if I ever did it again

 

i agree. ive had a na 5 speed. uk auto bpu and jpspec single 6 speed. the auto BPU was a dream to drive.

[tooquicktostop]

Would you just go basic BPU or everything possible at the BPU level whilst keeping the sequential system?

 

UK brakes, new intercooler and basic bpu is enough, I did hybrid turbos, 550 injectors, Syveccs bpu and the gains were minimal compared to cost

[Frank Bullitt]

UK brakes, new intercooler and basic bpu is enough, I did hybrid turbos, 550 injectors, Syveccs bpu and the gains were minimal compared to cost

 

I wasn't so concerned with cost VS gain, the way Stu Hagen seems to have gone looks interesting apart from the change of sequential to parallel.

[baldy]

Stu hagen is running sequential, this is the route im looking to take, just waiting on the new manifold hes working on

[Frank Bullitt]

I thought he had gone parallel for some reason, you aren't the only one waiting on his manifold

[mellonman]

I have said it many times if you put the sequential system in parrel you may as well just go single , even the stock turbos are laggy as hell that way hybrids would be worse , dont let the mapper say they make more power out your hybrids that way they dont ! It would be exactly the same its just so hard to map in sequential, unless your piggy back ecu that is

[fastcar]

I would say the only way to increase 0-60 times is to increase rear mechanical grip! Increasing bhp or torque wouldn't have much effect on 0-60 but more on 100 to top end!

[Fulcrum2000]

So is there a limit to any PU I can do as I have a JDM Auto? Someone here is saying they only handle up to 500HP? If I spent a lot and went big single I guess I cant alter the gearing anyway so I would have a glass ceiling of performance?

[Frank Bullitt]

If you are running the autobox you want the 3.769 ratio, you can get this in a small A diff (easier to find) or the larger B diff (like rocking horse poop and a lot more expensive). If you plan on going over 600+ and abusing the car you want the larger diff. You will also need a propshaft and both drive shafts depending on which option you choose.

 

DavidP offers a Hybrid box, contact him for more info if this interests you. Loads of reading here - http://www.mkivsupra.net/vbb/group.php?groupid=57

 

You can get upgraded internals in the US from ATF Speed and Raybestos Blue Plates from Import Performance Transmissions. Fitting both of these will allow the box to handle more power and any good reputable auto box builder in the UK can do this job for you.

 

You can get ready built boxes from the likes of Titan Motorsport, ATF Speed and maybe Boostlogic. Personally I'd go with ATF speed (see videos in the first link below). I am not sure if the latter of these is still making them and one of them (Titan or Boostlogic, I can't remember which now) gives a hefty shunt when you select reverse gear.

 

E2A

 

More info and some videos here - http://www.mkivsupra.net/vbb/showthread.php?341705-Facelift-auto-box&p=4214612&viewfull=1#post4214612

 

Built autobox currently for sale here - http://www.mkivsupra.net/vbb/showthread.php?337128-Boostlogic-auto-box-rebuilt-to-withstand-750-lb-ft

Edited May 15, 2017 by Frank Bullitt
Links added. (see edit history)

[Scooter]

I would also tweak the first turbo pipework so it raises the boost at low rpm's slightly. I had stock tt's for years and only in the last couple have I had a bpu one. It wasn't as nice to drive with the standard 0.7 bar to 1.2 jump on the transition, with the first turbo tweaked to give 0.9 and my restrictor ring to limit the second to 1.15 ish I find it a lot nicer to drive, good torque and response at normal cruising rpm and the usual top end power. I found there was no gain (even felt worse to me) in the first turbo zone with my bpu car (this was driving them back to back) and as we tend to spend the vast majority of the time in this rpm range I value the extra boost down there.

 

Saying this, some love the harsh/violent transition rush.

[squiffy]

I would also tweak the first turbo pipework so it raises the boost at low rpm's slightly. I had stock tt's for years and only in the last couple have I had a bpu one. It wasn't as nice to drive with the standard 0.7 bar to 1.2 jump on the transition, with the first turbo tweaked to give 0.9 and my restrictor ring to limit the second to 1.15 ish I find it a lot nicer to drive, good torque and response at normal cruising rpm and the usual top end power. I found there was no gain (even felt worse to me) in the first turbo zone with my bpu car (this was driving them back to back) and as we tend to spend the vast majority of the time in this rpm range I value the extra boost down there.

 

Saying this, some love the harsh/violent transition rush.

Scooter, Can you elaborate on the 1st turbo pipework?

I've been thinking recently how I want more out of the first turbo

 

 

[ianhid]

I love the rush on 1st to 2nd turbo cut in with BPU, gives you the grin factor. For me it's about how a car feels that makes it enjoyable, I'm not actually that fussed about total power output. If you were making a track car I can see why you'd want to smooth that changeover as it could unsettle the car and more boost on 1st turbo == more power overall.