Rb26 Gt-rs Dyno Result

[CruiseLiner]

gotta love the smoothness of a billet crank, compared to the others

[Mik]

Is that in reponse to my #1?

If that is the case, then I am not sure that we are talking about the same thing.

With the longer rod, the piston is around TDC longer for the same number of crankshaft rotation degrees. Hence “around longer” means while the combustion is actually occurring, That’s why I say “Thereby giving an increase in combustion pressure, this means more torque per firing”.

The angle of the rod at ½ stroke is something altogether different. Where the longer rod is also an advantage as the right angle to the crank occurs earlier in the combustion process. Therefore imparting more torque at that time.

Or have I missed something?

cheers

With a lower rod ratio, the rod will be normal to the crank earlier in the combustion cycle, not later (ie. closer to TDC, meaning more force transfered to the crank pin and more torque.

But I agree with you, if you want an engine to last, especially at higher rpm, longer rods are better.

This page explains it well: http://e30m3performance.com/tech_articles/...namics/dyn2.htm

[mark99]

Hey guys, once again thanks for the interest, when i started this thread i thought the interest would centre aronud the gt-rs turbos, as these are always the centre of debate...

Again though please dont think im trying to say what i've done is ultimately better than using a brand new jap brand stroker crank, most of those cranks are a real nice bit of gear. However, value for money i may be able to compete on. For me it was just time as i have all the equipment at my disposal, but im in the midst of trying to figure if i can do this conversion at a cost that is both economical to me and to customers. To do this ill have to be well under the price of those kits. Im thinking that this conversion is good for people who've just trashed a crank through oil surge, and are looking at building a new bottom end, and need another crank anyway. One other thing to think on is while my crank is not fully counterweighted, this may be a good thing for a drag application, as fully counterweighted cranks are quite heavy. Lightweight cranks are always limited life but for drag work often this is not a worry

[R31Nismoid]

I think we've bashed the GT-RS topic enough and they only really work well on a stroker/RB30DET

The crank however is something very new for and interesting for us all

Good work

[Swiper the Fox]

We have GT-RS turbo's and will change back to 2530's if i can't overcome the lagginess (is that a word) of them. Larger capacity seems the only answer.....or a shot of gas off the line to spool them up quicker. mark99 our car is drag only so may be a candidate for your crank upgrade.

Disclaimer: The above post could be and possibly is total bullsh1t

[CruiseLiner]

just a note my jun crank weighs EXACTLY the same weight as the factory cast rb26 item. 19kg i think it was

[discopotato03]

While on this GT2530/GT-RS(2871R-52T) has anyone thought of using HKS's GT2535 turbo's ? From their specs they use the same turbine as 2530's and GT-RS's but the compressor is an unusual 69mm diametre so may prove a little less laggy than the GT-RS's 71mm compressor depending on wheel trim and housing AR . I have to assume its compressor is a special by Garrett for HKS which they do at times . I'm not sure if its available with housings to suit an RB26 but its food for thought .

Cheers A .

[B0BB0]

top work mark, it will be intreasting to see what happens when u turn up the power levels.

Hows your stagea going brad ?

[Mik]

We have GT-RS turbo's and will change back to 2530's if i can't overcome the lagginess (is that a word) of them. Larger capacity seems the only answer.....or a shot of gas off the line to spool them up quicker. mark99 our car is drag only so may be a candidate for your crank upgrade.

Paul...when you say 'lag', do you mean throttle response (as in how long boost take to build when you open the throttle at enough revs for boost) or boost threshold (as in how many RPM are needed to build boost)

I always found the GTRS to be excellent as far as 'lag' goes.

What does your boost curve look like now? With the same cams as you have and a stock engine, I had 1.3 bar at about 4800-4900 RPM. That's not too bad, it's only a couple of hundred RPM worse than 2530s or 2860Rs. That was without any funky cam timing too...was running 110/113 (or whatever PONCAMS run...forget now) lobe centres.

Grab a laptop and head out to the track and play with the spoolup. You should even be able to do it on the freeway as you don't need to be doing ridiculous speeds to tune the spoolup area.

[Swiper the Fox]

Paul...when you say 'lag', do you mean throttle response (as in how long boost take to build when you open the throttle at enough revs for boost) or boost threshold (as in how many RPM are needed to build boost)

I always found the GTRS to be excellent as far as 'lag' goes.

What does your boost curve look like now? With the same cams as you have and a stock engine, I had 1.3 bar at about 4800-4900 RPM. That's not too bad, it's only a couple of hundred RPM worse than 2530s or 2860Rs. That was without any funky cam timing too...was running 110/113 (or whatever PONCAMS run...forget now) lobe centres.

Grab a laptop and head out to the track and play with the spoolup. You should even be able to do it on the freeway as you don't need to be doing ridiculous speeds to tune the spoolup area.

boost threshold...there is now a 1000rpm hole in my torque curve...ie. similar power and torque as before but 1000rpm later...but in saying that, we made more power but later on in the rev range and still climbing at 9500rpm. I don't want to rev the guts out of it to make the similar numbers as before and the off the line torque of the 2530's is now gone. Dropping it at 8500rpm-9000rpm off the line is bogging the car on launch...instead of 1.4 60' times with instant throttle response and the tyres on the limit of grip.

[rb26s13]

hey dirt garage any chance of seeing that dyno sheet? also i remember hearing somewere that a rb26/30 at 7000rpm or was it 7500rpm will make the same power as a rb26 will at 9500rpm?

so yer power still climbing at 9500rpm.. maybe more cubes is gunna have to be the option?

[Guest Mashrock]

this is nice.

i beleive i have a vl crank around here somewhere.

will hang onto it just incase!

[Swiper the Fox]

any updates??

[Guest Mashrock]

Bump.. needs to know

[mark99]

Sorry in the delay with updates, been absolutely flat out....

I put bigger injectors in and the car ended up making 406rwkw @ 18 pounds on pump fuel. Any more boost and it only picked up small amounts of kw and started to heat the air, not sure if the turbos are maxed out or if something in the induction setup is causing a restriction... not sure if my cooler is big enough. I've got another dyno sheet but its done in shoot 8 insted of shoot 6 so the torque figure is different due to the different ramp rate?? ( i dont know much about dynos). The power curve looks identical, just goes a few kw higher... To drive, the car is nice and broad and controllable in power delivery,pulls well from 3000 rpm and hard from 4500 through to 8500rpm...

Ive two more cranks almost ready to go, and more started for those that are interested. Please PM if you are intersested, so we can discuss options. It can be set up with std rods, or after market, 21mm or 22mm pins. My car will be on display at Adelaide auto salon, as will a 2.9l short engine. As usual any questions, comments or ideas just shoot

Mark

[Guest Mashrock]

Ahh nice work mark,

what price would someone be looking at for an engine built. would you be able to break down the costs also.

Looking good otherwise! i'd see this as a nice setup for the new large singles that have been comming out recently.

[rb26s13]

Ahh nice work mark,

what price would someone be looking at for an engine built. would you be able to break down the costs also.

Looking good otherwise! i'd see this as a nice setup for the new large singles that have been comming out recently.

and for those of us that cant fit a 3litre underneath due to not wanting to get rid of the stock bonnet

[Ronin 09]

pics of the crank and short motor if possible, mark?

cheers

[mark99]

Im from Rhemac Motors, we are a performance engine machining shop. Prices for a built engine really would vary, depending on brands of parts used, std rods or aftermarket, how big a cams etc etc. PM me a phone number and i can call you. But ball park, crank and custom CP pistons, pins and rings $4000. By the time you did a whole engine and assembled it, start around $9000 - $10000 depending on what options, and then go from there with yet more options. Ill try take some pics on the weekend and post em up

[Guest Mashrock]

Thats ok mark, i'm not actually looking at getting this done as i am happy with my setup and i dont have money for engines at the moment. possibly more a future thing.

i understand that there is alot of variation in engine building and final cost would vary alot.

still glad to see this, and hope all goes well.