BK, about time for a build thread ? - 1995 R33 GTR V-spec twin turbo

[BK]

R33 accepted into Elite show hall for display before Motorkhana, which will be going for its 3rd win racing. Going to ditch the drags in this car. It does 11.5 at 120mph so I'm done with risking any further drag racing related stone chips, as ASID track is very gravelly. Top fuel cars are going to hate it.

[BK]

Got the 33 into the Elite show hall so it will be on display until Motorkhana Sunday racing. Drag racing with the two 32s Saturday.

[BK]

Ok RCN 08 is done for 2022, so I'll debrief here. The R33 GTR above won top Japanese car for the event in the elite show n shine component. The car is immaculate inside and out really for a 27 year old car with a genuine 81500km, hence the retirement from ever returning to a drag strip.

The racing for the weekend didn't quite work out as planned. The two 32 both ended up having issues at the strip on Saturday. White 32 shit a CAS restricting timing to a max of 5 advance, so as you could imagine it knocked the shit out of producing any power. I checked this after it's first and only run after it clocked a laughable 105mph 😆

Cue the blue 32. After a previous shakedown of 139mph, I put it back on E85 and was reading consistently over 70% ethanol content, so I decided to send it. I re-enabled launch control at 6500rpm and full boost at 32 - 33psi. Launched of the line at a not so great but ok 60ft of 1.82 and proceeded to smash through the gears until I lost power at top of 3rd when changing into 4th. Sensing something was wrong I backed out of the run at about 3/4 track and coasted through at 11.51 at 128mph. On further inspection let's just say something stopped the blue 32 from continuing on that day, meaning an early retirement from the strip on Saturday so we could try and rectify the cars for the Motorkhana event on Sunday.

After "fixing" the blue 32, swapping the crank angle sensor out on the white 32 and picking up the 33 we headed out to the Motorkhana with all 3 cars ready to race. The Motorkhana event on Sunday was bloody awesome with all 3 GTRs performing flawlessly with no problems unlike at the drags. My impression from the Sunday event:

-White 32 handles awesome and has a heap of power. The 6466 1.00 a/r is not too big for the 2.6 and was definitely very very responsive and great on / off throttle response. Amazing what the correct and accurate timing did for the car.

-White 33 performed as expected - It grips, turns, stops and has a great balanced power delivery. Nothing new there.

-Blue 32 🥰 What can I say.... Only thing to say is HOLY F**KEN SHIT !!!!! This car initially scared that shit of me out there as the power was frigging insane ! This was the car I drove the most on the day as it was just so much fun - I've never driven a car with this much power in an environment like this 👍After getting used to the 600kw + with the imposing concrete and water wall barriers, the car was awesome in its handling, traction and mind numbing power delivery - very confidence inspiring 😃

So in a wrap, the fastest GTR out of the 3 at the event was.....

 

THE 33 WITH THE TWINS !

 

After winning the 2020 and 2021 event I couldn't make it 3 years in a row, by a tenth, securing 2nd place overall from just one try in the 33. The 32s with the single 6466 turbos were just too aggressive with too much power on this type of track, but were way more fun to drive ! TBH I think the blue 32 COULD be the fastest with more skill and practice behind the wheel, but really just showed that the 33 was just a much easier car to drive fast on the limit. Overall a pretty successful outing considering there were no major failures during the event. First time for everything eh ? 🤣

Until next time 👍

[r32-25t]

I can’t wait to see what the blue one runs when it finally gets a clean run, 

[Duncan]

Sounds like you had a hectic but fun weekend.

And....

Of course twins > singles

[BK]

On 14/09/2022 at 5:58 AM, Duncan said:

Sounds like you had a hectic but fun weekend.

And....

Of course twins > singles

Defintely hectic, but heaps of fun  Regarding the twin vs single debate it was a good back to back to compare pro and cons of each.

The biggest issue with the singles is they have soooo much power, which upsets chassis balance in something like a Motorkhana with such tight conering. When the twins come on the power is delivered in a much more manageable way. In any other situation the singles are the far superior choice as the throttle response and spool up is great, matching or exceeding what the twins were capable of but with much more power being harder to control for mere mortals like myself.

In my opinion, only power levels of 350kw or lower should twins ever be considered as an option, as the singles from here on do everything better.

[Piggaz]

On 14/9/2022 at 10:15 AM, BK said:

Defintely hectic, but heaps of fun  Regarding the twin vs single debate it was a good back to back to compare pro and cons of each.

The biggest issue with the singles is they have soooo much power, which upsets chassis balance in something like a Motorkhana with such tight conering. When the twins come on the power is delivered in a much more manageable way. In any other situation the singles are the far superior choice as the throttle response and spool up is great, matching or exceeding what the twins were capable of but with much more power being harder to control for mere mortals like myself.

In my opinion, only power levels of 350kw or lower should twins ever be considered as an option, as the singles from here on do everything better.

But you’re comparing a single that flows ~600 kw vs a 350 kw twin setup so of course the single is going to hit like a ton of a bricks, anything would.

Put a single on that flows 350 kw, the same as a set of -9’s and see what happens. 🤷‍♂️

[BK]

On 14/09/2022 at 10:06 AM, Piggaz said:

But you’re comparing a single that flows ~600 kw vs a 350 kw twin setup so of course the single is going to hit like a ton of a bricks, anything would.

Put a single on that flows 350 kw, the same as a set of -9’s and see what happens. 🤷‍♂️

Absolutely mate I know that and totally agree. Who in their right mind would bother doing a single conversion to get max 350 kw on an RB26 ? That would be like a baby Precision 5558 or so and don't even know what that would be in EFR.

The point I was trying to make is you can pretty much have a single that roughly comes in the same time as small twins but a LOT harder, as well as being able to deliver double plus the power. The singles were in no way laggier, but delivered the power in a much more aggressive way on the road.

Cake and eat it too results I think when it comes to singles. The two white cars are both 2.6, running the same 20psi boost and spool from vac to boost was similar - but even on low boost with the 6466 the power delivery is much more savage compared to the twin hks gt-ss / -9's translating to a car that was much more of a handful.

[Lithium]

On 14/09/2022 at 12:57 PM, BK said:

Absolutely mate I totally agree, but who in their right mind would bother doing a single conversion to get max 350 kw on an RB26 ? That would be like a baby Precision 5558, don't even know what that would be in EFR.

I guess the point I was trying to make is you can pretty much have a single that roughly comes in the same time as small twins but harder, as well as being able to deliver double plus the power.

Cake and eat it too results I think when it comes to singles.

I love this discussion, brings out some interesting and valid points.  I've never argued hard against people chosing to stay twins at 350kw as really the single benefits aren't going head and shoulders away from twins YET.  I still prefer them, but the argument is less one sided.

Now in regards to the high power vs control thing, this is really what got my attention in this discussion - we at the best of times get hard ons for showing and bragging about epic power delivery but the reality is often what matters SO MUCH with racing is making the car driveable, and reliable.   A good number of the turbo race cars I've tuned we've done a lot of work in managing the torque to keep the cars predictable, and it can seem like you're just leaving stuff on the table for no use - but honestly its amazing the difference you can make giving what people may grumble and call a "peaky" power delivery.   No point making it hit like a train if you are going to be all over the show trying to keep the car on the road.

An option you have with the likes of your 6466 that you don't with the twins is you can more or less tune the 6466 to do stuff that makes the twins good, but you can't do the other way around.   As a hypothetical thing, if you look at the dyno plot for the twins - which you know you can control the car with nicely then identify the peak torque you make with them, then select a boost curve with the 6466 that never exceeds that torque.... but ramp the boost up to carry the torque to the far end of the dyno plot, instead of letting it plummet like the twins do then you potentially have some degree of having your cake and eating it too.     Well maybe a 6466 is a bit more snappy/laggy transient wise than the EFRs/G-series that I've played with but you'll get the gist of the what I'm saying?   

I've done this kind of thing with numerous FWD/RWD/even 4WD race cars when creeping up in power levels where the owners have decided to try the suggestion as an "in between" while working up with a bigger setup and then ended up finding that it actually at least in those cases made the car easier to drive faster and is generally less hard on the car on the driver and been relatively happy leaving it there.

It may seem counter intuitive when we work so hard on finding ways to improve torque, but really in a lot of cases the "how hard is it to get to the torque I'm looking for" is a lot more important than "how much torque can I make?" when you're trying to go fast.

 

 

Edited September 14, 2022 by Lithium

[Duncan]

So, I totally didn't mean to start a serious discussion, but clearly at (relatively) low power levels, standard configuration twins are perfectly adequate for competitive use.

Depending on race category rules, response can be everything. The BSM national champs winning IPRA car ran smaller than stock twins due to the intake restrictor requirements, and N1s are perfectly adequate in production car racing too.

Even in a case where the rules don't limit power, it can absolutely be better to trade off 500rpm for 100kw or more at the top end, as BK just demonstrated in the motorkhana....500rpm can take forever sometimes....

[BK]

On 14/09/2022 at 11:10 AM, Lithium said:

managing the torque to keep the cars predictable, and it can seem like you're just leaving stuff on the table for no use - but honestly its amazing the difference you can make giving what people may grumble and call a "peaky" power delivery.   No point making it hit like a train if you are going to be all over the show trying to keep the car on the road.

^Pretty much this mate, spot on. It wasn't that the 6466 cars were laggy at all, just they delivered actually way too much mid range torque to be usable compared to a much more predictable / not over the top power delivery.

[Lithium]

On 14/09/2022 at 2:06 PM, BK said:

^Pretty much this mate, spot on. It wasn't that the 6466 cars were laggy at all, just they delivered actually way too much mid range torque to be usable compared to a much more predictable / not over the top power delivery.

Overall sounds like a lot of fun

[BK]

On 14/09/2022 at 1:30 PM, Lithium said:

Overall sounds like a lot of fun

Yeah it was great pushing the cars. I was really impressed with the Hankook RS4 on the 32s, as it was the first time I'd used them in competition. The 33 that day was on the Advan AD08R and might be a factor on it being quicker ?

Not sure really as both gave heaps of grip.

[Duncan]

well, you should put proper semis on them for the khana next year, some soft yokos A050 or hankook Z221, they are just mind blowing compared to street tyres

[BK]

Car has done nothing since September, but I did get around to refixing the genuine front bonnet lip on properly with new mounting hardware. My under bonnet insulation pad is now annoying me and probably needs a replacement as heat is starting to affect it, but I think they are drug money price now so probably won't happen.

 

[Dr Evil]

Yup, mine rattles too...........

[Layne Smith]

I saw all 3 cars on my way to work! Only time of the year I actually like working 🤣 Was an awesome sight. Shame my R32 broke down a month before the event  Always keeping my eye out for the skylines. Also saw a black 33 GTST on the back of a truck heading to Barrett Drive.