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Oh, and to give a comparison, I could have babied mine around like a grandma, but all of my Kays were driving to and from driving events and at the events. I did 2 track days on one bottom end (Well, actually 3 sessions at half pace each day) and then one texi.

The other one managed to get tuned on the dyno, then make the 3rd session at a track day and everything let go.

Slappers on big turbos do NOT last long...

I've broken 2 now... With a max of 1000KM on them... Pushing 1Bar (14PSi) through TD07S housings, t66 front and a t04r rear wheel.

Nothing below 4000/4500RPM, then everything ramps in over 200/300RPM...

Rev limited at 6600RPM.

On the dyno it made "250RWKW" wheel spinning like a spastic... Using fuel consumption and AFR it would be making around 360RWKW... (69% inj duty on 880cc injectors)

so they were used bottomends not refreshed or anything with twin cam head and big turbo on them?

could i expect anything different considering its got new pistons and bearings?

what exactly let go on them? rods bend or pistons break or the bearings finally had enough or what?

wanna get more than 1000kms out of my rebuilt one hey. if it was a full slapper i wouldnt give a rats. it was meant to be cheap as shit then i decided to go new rings and bearings to refresh it then found i had to bore it out and new pistons. also got the rb25 head full rebuilt so spent extra $750 more than i planned to there. probably just gunna put standard rb25 turbo on it for now but to get some use then il put the big shit on it and wont feel so bad if it lets go.

The bearings will not let go as they are the3 same as the bearings used in aftermarket rods

The rods will not bend until about 600hp or if the tuner detos the engine

the pistons will crack if deto is present but so will forgies they just have a bit more tolerance.

Its all down to your tuner if he is good then your not going to have issues

so they were used bottomends not refreshed or anything with twin cam head and big turbo on them?

could i expect anything different considering its got new pistons and bearings?

what exactly let go on them? rods bend or pistons break or the bearings finally had enough or what?

wanna get more than 1000kms out of my rebuilt one hey. if it was a full slapper i wouldnt give a rats. it was meant to be cheap as shit then i decided to go new rings and bearings to refresh it then found i had to bore it out and new pistons. also got the rb25 head full rebuilt so spent extra $750 more than i planned to there. probably just gunna put standard rb25 turbo on it for now but to get some use then il put the big shit on it and wont feel so bad if it lets go.

It comes down to the tune and how you drive it.

My first one let rip with oil surge on a track, mixxed with an over rev when it stepped out in second gear. Well that was the initial thought. Now it appears that the thrust bearings had worn out massively allowing the crank to float and just annhilate everything.

The second motor let rip with what appears to be a cracked oil pump. But this motor spent a shit load of time living life on the hard rev limiter at a motorkhana (Big turbo, very hard to get it to keep the tyres spinning at part throttle without hitting the limiter, if it didn't hit the limiter it bogged and died).

If I drove these motors peacefully, I'm near on 100% sure the second one would still be together today (The first one, probably not... It was a PITA from the get go)

If you can break rods, you're going well. Pistons may let go if it's not tuned properly.

The biggest killer is normally oil control, get a good oil pump on there and doa winged/baffled sump especially if you plan to do ANY form of drivig events (Even if you only do one!!!)

My first one let rip with oil surge on a track, mixxed with an over rev when it stepped out in second gear. Well that was the initial thought. Now it appears that the thrust bearings had worn out massively allowing the crank to float and just annhilate everything.

IMO that's the biggest risk with a slapper. My first 30, even though it had forgies, was a slapper crank and rods and the thrust clearance was out.. destroyed an oil pump and almost the block :(

Second pass, I got the crank ground for oversize bearings and it lived a much healthier life (only pulled it apart to upgrade rods and other stuff).

The bearings will not let go as they are the3 same as the bearings used in aftermarket rods

The rods will not bend until about 600hp or if the tuner detos the engine

the pistons will crack if deto is present but so will forgies they just have a bit more tolerance.

Its all down to your tuner if he is good then your not going to have issues

thats it, GOOD tuner

  • 1 month later...

469rwkw on a 3l slapper is the current record in my shop, nothing like a time bomb :/

Slappers FTW if their mates cars who can deal with the consequences if it lets go... a no no for customers :P

Dont just say a figure like that and not give us the details

Sounds awesome I want to know more

std rb30 na bottom end, 26 head and t04z.

about to kill it with a std 1.5jz thats in the shop atm, we matched the output of 469 last thursday... shooting for 500 by the end of the week.

btw both on e85.

  • 2 weeks later...

looks like i got the only genuine slapper here, 285kw@14psi 6800 rev limit

Rb25 s2 Head Fresh Mill clean slapped on to..

Rb30 s11 Bottom end 70,000kms. Un opened.

ACL 1.3mm Metal Head gasket.

GT35r,

and other stuff but not important here.

not daily driven but 6 dyno tunes, 1 sau dyno day, 2 wakie days, 1 hill climb and 1 motorkhana. love it

i'll let you know how long it lasts...

you have a metal head gasket, not a slapper :down:

i've just got myne running a few backs, still tuning atm but i'm running 23psi from a 1.06 gt3076 through an unopened 150k bottom end, standard nissan gasket etc. will get it on the dyno after tuning to see how much power its making

  • 2 weeks later...

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