Single turbos and lag on 13b REW
 

What's the largest single turbo one could use on a 13b REW with a street port before lag becomes a big intrusion to throttle response? My application will not require very quick throttle response, but mid range power and response will need to be retained.

Thanks for any help.

It's a simple trade off. How much lag can you tolerate versus how much power you want.

I went with a T61 turbo with a .84 divided housing in a Q trim. Some say this will be laggy on the street. We'll see.

Steve

Hey Mike!
How much power are you looking to make?
That normally determines the size of the turbo you'll need.
Also what type of racing are you going to be doing?

crispeed
87TII
9.67@141mph
608RWHP/449RWTQ

Steve!
Whoever told you that a T-61 with a Q-trim .84 divided housing is going to be laggy obviously never had one!:):)
I hope you're using a divided manifold with that turbo!

crispeed
87TII
9.67@141mph

What's a good turbo to use to get around 380-400 RWHP at around 15psi? I'm slowly working my way to a single and am looking for ideas. Also, where's a good place to learn all the terminology like diff trims and what not.

a T61 with a .84 housing being laggy..no way..it should spool quite fast but your top end will taper off with a .84 for sure

Thanks for the help.

I am looking to make about 400 flywheel horsepower and I don't want to use a lot of pressure.

I am not going to be doing any racing. It is going to be for a boat. Around 24 feet in length overall. I will mainly be using it for cruising, so lag will not be an issue with most of the piloting being done at a continuous rpm, but I will need good mid range power to get the boat on plane. When the boat is on plane, it presents the smallest amount of displacement in the water and therefore the hull has the least resistance. The faster the boat gets on plane, the faster it accelerates. :)

Hey Mike!
Have you figured out the rpm range you want the motor to be operating in? That would help determine the turbine size needed.
From what you have said before a 60-1 turbo at 12 to 13psi should give you the power you're looking for.
I knew a guy who did the same as you and he ended up using a 1.32 A/R turbine housing but his set up was a little different, smaller boat, higher horse power requiremnt etc. He was more into lake racing!

crispeed
87TII
9.67@141mph

Crispeed,
I am looking to put 425 to the wheels with my setup. I have the T61 w/.84 and a Q trim and divided housing as stated above. I also will have the E6K from Haltech, a front mount intercooler (undecided on which so give me your opinion), NOS (to be used rarely), Fluidine radiator, stock ignition (so far), Pettit LARGE street port (sounds like a bridge at idle), Fresh rebuild by Japtrix (great guy), Custom built filterd ram air, Aftermarket vented hood, T78 exhaust manifold, Inovative turbo wastegate, and lots more little items I can't think of at the moment.
My goal is to have a streetable 400+ RWHP without the NOS. If this turbo is not up to the task then let me know what you think. I'm no expert on turbo maps. I thought that with an RPM limit of 8 grand this turbo would put out the right amount of flow to peak just before the RPM limit. I was only told that it was laggy by one person. He said the Q trim was a mistake. I thought the Q-trim would be more durable.
What type of exhaust would you sugest on the street with this. I can weld stainless and was planning a custom setup. I have looked at some 3.5 and 4" race mufflers to work with this. What do you think?
Give me your honest opinion Crispeed. I know you know your shit! Also would you consider tuning this setup once I build it? I don't want to put it all together and have to yank the motor because I leaned it out and blew it up.

Steve

I agree that the HP that you wanna make should constitute what turbo you should use, getting a turbo that will give you good response with 400HP is an easy task with a rotary due to the exhaust pulses being so strong. In any case make sure that you get a backhousing a little on the big side, rotaries like I said have alot of exhaust pulses and they need bigger backhousings than a comparable piston motor, especially if you want to use NOS in the future. Running NOS in a RX with a small backhousing will cause the turbo to overspin and become inefficient, and therefore the car will not produce any more HP than it would with the NOS turned off, just more heat.

I had planned to run the NOS only in the lower portion of RPM before the turbo makes much power. Only in a streetrace from a slow roll or a dead stop. I was gonna set it up as a 50 or 75 shot. It is adjustable.
As far as housings I am not oposed to buying a larger housing if I need to. I can't predict exactly what kind of responce I'll have with this setup.
I want full power pretty early since it's a streetcar, but I also want good top end. I thought what I have is a good compromise.
If you think otherwise fell free to make suggestions since it's going to be bolted in soon.

Steve

Hi guys,

Lag is directly proportional to the size of the journalist who invested the word's balls :)

Personally I think there is no such thing as lag, only a delay between hitting the loud pedal and the fun starting :)

Seriously though, if you are only after medium power with good response, one of the Garrett BB range of turbos would be perfect. The GT30/35 would be spot on I think.

A friend of mine has one on a T2 engine and its making 360 rwhp (on dyno dynamics which would be over 400 on a dynojet) and lag is virtually zero. Car has run a best of 11.1@117 (car was missing up top!) and thats in an 83 1st Gen.

I have a Cosmo 13B which is almost the same as a 13BREW and I have a hybrid turbo with a T72 size front and a Q trim exhaust blade with a 1.22 divided housing. It takes some time to spool up (about 4200rpm) before it comes on full song, but when it does hang on!

My turbo is on the left, and a 60-1 with 0.70 marine cover is on right.

http://members.optusnet.com.au/~manchild/turbo-5.jpg

My turbo is on left and next to it is a 1.15 exhaust with a P trim blade.

http://members.optusnet.com.au/~manchild/turbo-4.jpg

This is my turbo next to a 13B rotor, just to compare sizes.

http://members.optusnet.com.au/~manchild/turbo-3.jpg

Yes, it is a bit laggy, but it is worth it. Car has made a best of 334rwhp on a dyno dynamics (380+/- rwhp on dynojet) on 12psi and a weak ignition spark. On the same night we put C16 in it and attempted to tune it (this is when we found the spark problem). The car made 20psi by 4000rpm and made 375rwhp at 6000rpm on 20psi before breaking down due to spark issues.

At the moment the car is at Haltech in Sydney having the ECU re-wired as there were a few problems with the way I installed it :( When I get the car back, it will be tuned for 20psi+ and C16 and then I go racing :)

Thanks for all of the help.

I don't think 20psi by 4200rpm is laggy.

AJC13B, What rpm is the motor at when you start to make positive boost? i.e. 1psi and onwards?

With the C16 in it the car spooled up alot quicker because Matt could advance the timing a fair bit.

With pump fuel, it will start making positive manifold pressure by 3500rpm but it woun't pull until past 5000rpm and 10psi.