Jump to content
SAU Community

Recommended Posts

  • Replies 73
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

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

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

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

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 .

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.

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.

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?

  • 1 month later...
  • 3 weeks later...

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

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 :dry:

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.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
×
×
  • Create New...