Fastrotor

Ferodo do Marko.

Why did you leave the top hole open when you seem adamant about sealing the rest so well ? Only downside to all that dynamat covering the holes is if something needs fixing. If i had some panels laser cut to suit, and dynamat'd them and screwed in place would this be ok ? That way i'd retain full easy access to the doors..... as i know my luck if i sealed them up like in the pics !. Gary

Thanks Noel, will be good to to see it better , see how it looks with the gtr front end on there. Gary

Noel, do you have any better pics of your cars rear guard flaring ? Being black , i found it very hard to notice what you had done in your other thread, whenever that was Gary Welcome to the club.. i have a spare forged 30 sitting inside the house too.. only cause i can't afford the 26 head work yet !! Tempted to just whack it under the current 5cyl RB25 for the sprint season.

I knew the calcs must be right, but i wondered what we both did wrong in the manual calcs..... and i just worked it out. When we did the volume of the cylinder for the gap below the deck, we used the 'diameter' in the "Pi*R2*H" equation ...stupid mistake but easy to do. So its definately 8.9:1 ..... cool.... now i can calc in confidence what i need to do to get it higher. Gary

Just for interest when dynoing a fwd N15 pulsar with sr20 turbo convo that had one of these 'varex' cannons , it was making 210 fwks's open. With it closed power dropped to about a 100 But very quiet though !

Hmm seems like somehow our manual calcs are wrong.. i've used quite a few different calcs , and finally the standalone calc for comp ratio and Dynamic comp ratio from Pat Kelly , what a great little bit of software that is. They all gave over 9:1 so i guess its fine. Anyway i cc'd one cyl on the head and got 65.5cc so the actual comp works out to 8.9:1 ... which id still like alot higher , due to wanting to run 280 degree cams. Either that or get VCT on the inlet cam to raise the Dynamic comp ratio drastically down low. Gary

My Deck clearance IS 10 thou, (0.254mm) BELOW the DECK , i measured it from the deck to the piston flats at tdc. Seems pretty suspect if we enter 2.54mm in the calculator, that it shows the exact result we both manually calculated from the values. Makes me think the calc has a decimal place bug perhaps. More worrying is that it seems the motor is 7.7:1 ........ Im going to cc the heads tonight, then whack it on with gasket and tighten it all down an cc the whole lot to be totally sure. As for the deck height , there is no point measuring this one as it has been shaved down.... i need to know the original deck height to work out how much has been removed. I would have though with all the guru's on here someone would know......(and confirm our manual comp calcs) ! Gary

I just worked it all out by hand, and i get 7.7:1 same as you .! Now im worried. Engine builder says it will be 8.7:1 My results by manual were.. 3.426cc Effective piston to deck clearance 7.051cc Headgasket volume 64cc assumed head volume =74.47cc at TDC Piston bore volume at BDC (using 86.5 bore and 85 stroke) is 499.5cc Add the above value and get 573.97cc and divide by the 74.47cc = 7.7:1 Why do i get the feeling something is wrong......hopefully with the calcs !! Gary

Something is wrong for you to enter the same numbers and get a different result. Here are the exact numbers in order of putting them in. 2 86.5 85 87 1.2 64 11.5 0.254 = 9.17:1

Its really just an rb26 and your just telling everyone its a 30 ? hehe

No guessing it was yours that was better Paul, obviously. But , by how much is the real question. I'm guessing i'll get a cryptic answer, but have to ask ! Gary

Dave i wanted to know the stock rb30's Deck Height, not deck clearance. So i can work out how much has been shaved off my block. (ie deck to centerline of crank) No i used a positive value in the calc (.245mm) just as i measured it. The piston flats are just below the deck (.254mm) and the dome is above it. How did you get those values from the calc ??

what 9.5 run ? i only saw the 12 something at 95 ?? am i missing something marko ? Gary

Does anyone know for sure the stock RB30 DECK HEIGHT ??? Only reference i found on here was 230.5mm Gary

Hi Guys, I've just taken delivery of my RB30 bottom end. Now it was going to be 25 head, but i changed to 26 head. The motor came with ACL RB25DET pistons 6MKRY9603 's. Now i just spent abit of time on this site, http://www.csgnetwork.com/compcalc.html All the values are easy to get, except the deck height . So i actually measured it myself at .254mm (below) So these are the values i used below. 6MKRY9603 Bore 86.5mm Stroke 85mm Gasket Bore 87mm Gasket Thickness 1.2mm Combustion Chamber CC's 64cc (average of what i have read on here) Piston Dome CC's 11.5cc (off ACL website) Piston Deck Clearance .254mm (Measured) Gives a comp ratio of 9.17 : 1 If using the RB26 ACL Piston 6MKRY9604 Bore 86.5mm Stroke 85mm Gasket Bore 87mm Gasket Thickness 1.2mm Combustion Chamber CC's 64cc (average of what i have read on here) Piston Dome CC's 16.3cc (off ACL website) Piston Deck Clearance 1.254mm (Measured + 1mm as ACL lists the RB26 1mm lower COMPRESSION HEIGHT) Gives a comp ratio of 9.03 : 1 NOW ..... what i wanted to know is..... the comp ratios are very close, so either would suit, however the 1mm lower deck clearance on the rb26 piston, is this for extra valve clearance of high lift cams in the 26 ?? Will the 25 piston be ok in my motor with the 26 head and 260-280 10.8mm lift cams ? Hopefully someones been down this road. Thanks Gary

I have a BA falcon electronic throttle setup going into a top mounted W2A cooler on my 13B engine in my S4 Rx-7. Will be using the Link G4 extreme. Do you have the extreme ? The storm doesnt do FBW i believe. Last time i checked i don't think the link extreme had the E-throttle control enabled yet.... it was one of those able too, but not yet configured or something . Actually just checked , and yes, on there site they say "Electronic throttle control (available shortly)" ........ so you might want to wait until its Actually working ....LINK have a bad habit of having these wonderful options that never come to fruition...... which sucks ! If link haven't got the e-throttle working by the time i get around to finishing off the rotor, i'll just build a h-bridge driver circuit and control it directly myself, with just a 'tps' simulated feedback to the ecu. Gary

Just something i've though about too, why cant there be some sort of silicon damping between the pump and crank... ie like a silicon 'shim' so to speak to take up the slack and also damp the harmonics ??? I guess the worry would be it failing in time and the slack comes back, but hell, if theres that much slack already ..... ?... Gary

Hmm interesting topic for sure. Since head porting is a major part in making big cams work, i think this should be ok to ask in this thread. I was doing an excel spreadsheet of all the different rb26 head flow numbers i could get my hands on. Some were better than others in the mid range, some a bit better in the top end, to be expected , with differences in machine measurements and job expectations (we don't know they were all for a 'max' flow job etc. Anyhow point is, they were pretty close to each other with nothing HUGE standing out...... EXCEPT ...... Endyne......... and only the exhaust ports..... they were on top in the intake too but only by a small amount. On the exhaust flow results, most topped out at 190 odd cfm ................. there's was around 230+ cfm !!!!!!!!! Im peeved i seem to have deleted the xlsx spreadsheet else i would post. I guess i could redraw it if anyone was keen to see. So i'd like to hear from the guru's what they think. Paul, you being the RS guru, do you have flow numbers for your head please ?

Im getting custom metal guards made to do the rear and then just put on the gtr front end. As i like the S1 rear end better... these were only made in S2 rear. Gary

Hahah Phil, but when i say im making 650-700 hp ......at the wheels.... thru an auto ...... they all just tend to say FAARRRKKKKKK....so all technical conversation bullshit stops and they all become riceboy fans hahah Gary

hahah, simon i fly into brisbane monday, i'll come drive the 4door home for you, just to get to see the 3ltr gtr up close Haha My 3ltr bottom end gets sent this week finally, yay, so i might start my own 3ltr build thread soon ! Gary

There are so many factory setups out there now with vcam's, its a wonder noone has done it (commercially) before..... maybe perceived lack of interest. I tell you what, i'll have it as soon as its released..... then if its only inlet cam, i'd like a second one on exhaust and go crank trigger..... yea haaa .... I can see it now, sitting in the car on the dyno for hours and hours straight , playing with the tune ! And i'm lucky to have a hi-po 3ltr bottom end on its way to me next week finally ! Gary

I thought the same about the coupe rear fenders they do , can't say they look like a gtr fender..... more a compromise. This is not a job for the average panel beater..... its needs the attention of a wizz. I know just the guy up here in the north..... problem is getting his time !! What would be good is to know someone with an autech 4dr gtr so i could get some measurements....... Anyone got any really high res photos of the 4dr gtr's ? All the pics or vid online ive seen is pretty crappy....... need some good pics to show panel guy. Gary

Yeah let us know Dan, thanks Unfortunately the only rear fenders i've seen , including yours are for the coupe version of the gtst ... nothing for the sedan . Gary