2JZ in a Hachi, What about RB26DETT?

[NoHachi]

Ok, no hard feelings. No offence intended from me either.

To get this little thread back on topic:

Putting such an engine in a AE86 still isn't going to be easy (if it fits). Its not so much the horsepower, but the torque that the engine puts out. The extra torque will soon destroy your diff, but I'm guessing you already planned on using the some other sort of rear end (toyota pickup or something like that). If you can get the pumpkin to stay in place then the torque is transferred to the unibody. I have seen cars tear welds through (though it was on a honda CRX, destroyed the front subframe+mounts).
Be aware that cars are usually designed using the "engineering margin". Basically that means that the engineers at the factory calculated the force that is put on a part and then design the part with a margin of 2 (two times as strong as needed). When you approach the margin on a car that has already been put through a lot of fatigue cycles strange things can happen. Sadly fatigue failures are sudden and unpredictable.

The engine is a lot heavier than the 4A-GE, so you should ideally upgrade the braking capacity to suit (not just pads, but a physically larger system that can soak up the extra heat). The weight balance of the car will shift further up front, so plan on a brake bias valve and a custom set of springs.

When you adress al of these points (and some more I didn't mention) you will have one hell of a monster of a car, but you could start with any other car and have the same result.

Another suggestion that may annoy some the JDM lovers out there: Take a look at the Rover V8. Its the same engine as some sort of american V8 so there is massive aftermarket support. The difference with the US engine is that the Rover V8 is all alloy. That means this V8 is actually a little lighter than the standard iron 4A-GE. New engines are available from the UK putting out 300 bhp NA. Lots more to be had from forced induction and a lot cheaper than with JDM parts. Basically up to 2000+ hp in methanol burning drag racing application is possible (and has been done before). You'd have the same HP (and same problems that come with it), but a better overall balance in the car and a lot less weight.

[Mulisha]

Thanks for putting us back on track. No hard feelings, just a bunch of "engineers" butting heads. I was thinking of using the GTR differential and rear axle, eliminating the Hachi diff problem. Custom suspension came to mind as using Nissan 180sx or silvia front suspension and steering nuckle. Once that was inplace using 300zx brakes and rotors for the front and GTR rotors for the rear. The problems I forsee so far is getting a custom drive shaft. I have found no shop that has a drive shaft balancing machine. Oh and the fact that I cant ship the Hachi back to the states yet. So the original plan was to put the GTR engine temporarily in the hachi and ship the hole thing back as a parts car. Killing two birds with one stone. Euro hachi in the states and GTR engine in the states. First off In going to pull the Engine out of the GTR next week, and try to fit it into the Hachi. If it fits, then Ill go from there.


Mulisha

[NoHachi]

Hi,

Doesn't the GTR have a multilink/double wishbone hybrid rear suspension? If so, then you won't be able to use it on the hachi, it would be easier to fabricate your own double wishbone setup using ford sierra hubs. Mind you, the word easier is not completely accurate, you are redesigning the rear suspension and pickup points completely. The load paths should in no case go through the unibody, some sort of tube chassis should be fabbed to take on the load. Designing such a system either takes years of experience or a solid working knowledge of finite element computation programs and the forces at work. It would be more easy to just use the setup from a toyota truck or pickup.
The driveshaft should'nt be to much of a problem, there are plenty of companies capable of harmonically balancing it for you. Just look outside of the automotive buisiness. Another solution would be to reduce the need for balancing, a lightweight carbon propshaft reduces the amplitude of the vibrations and the energy content of the waves. At the raceteam I was with we used unbalanced carbon driveshafts (home-made), worked like a charm, even when dropping the car onto its wheels at full throttle. I know that there are several companies that produce these shafts commercially. If you cant find one in Germany, try Spinning Composites from Delft in the Netherlands.
Whether the GTR lump will fit is difficult to say. I know that it has been tried in the MX5 without much succes. The engine is too tall and long. I'm guessing to make it fit you'll have to make extensive changes to the firewall. A bit like the S2k powered AE86...
For reference, the V8 I mentioned is a compact unit and is mostly wider then the 4 cyl engine. They are a straight swap into a MX5 body with semi-bolt-in kits available. The AE86 engine room seems to be about the same size.
So proceed with caution on this swap. There is a reason that people walk certain roads, sometimes it is just the only logical road to take. I can understand though that not everyone wants to be logical, so I'll wish you succes for the test fittments.

[Mulisha]

Its got a rear multilink suspension. I havent really looked at the rearend, it was just a quick thought no ligic to it, sorry. Logical road...... something just clicked. If the RB engine fits without major adjustment to the engine bay then I will continue, but if I have to start remolding the firewall and such I will call it quits. This topic has really got you hung-up doesnt it? I guess you are just watching out for me, making me look at every angle. I appreciate that in a person.

Thanks

Mulisha

[NoHachi]

I'm really not trying to talk you out of it or something, just showing you the consequences of the choice for the large engine. To me defending the "small and light" choice has become somewhat of familiar debate. I participated in a year of FSAE racing car devellopment. When the rest of the field was running 300+ kg cars, powered by 600cc 4 cyl engines (max displacement for the class) from R6's and fireblades, we started devellopment around the ultra light idea. The final iteration of the devellopment was a 120 kg car with a mere 40bhp from a single cyl engine. Despite its massive lack of horsepower it outaccelerated almost every car at the competition, reached more than 2G's at the skidpad and blitzed the roadcourse. Its just a complete different line of thought.

Another argument for the balance story: at the last autocross there was a guy with a clio that packed a Megane cup engine (220+hp), full suspension, nice tires etc etc. At the end of the day he was just two tenths of a second faster than my MX5 despite having double the amount of horsepower and the same weight. The guy also had a lot more racing experience then I had, he said he lapped the nordschleiffe in 8:30 tot 8:40 BTG

Oh well, lets first see if the thing will fit in and take it from there.

[Mulisha]

fitment starts tomorrow

[NoHachi]

And and and! How did the fittment go man!?

[banpei]

PICS! SPECS!

[Mulisha]

the forklift that the shop uses was unable to be found. Couldnt forkit today. I have to work today adn tomorrow, will try this monday.

[NoHachi]

Any updates?