sorry if there had been a post like this b4 but i was reading about putting twin cam rb25 heads onto a n/a vl i was just wondering if doing this ment it had to be turned into a turbo (the 1 i read about was turned into a turbo) and how much power gain u would get by turning an rb30 into a rb25 twin cam with the rb30 bottom end also how much work is involved and how much approxx $? also any1 know how much insurance would go up with this head put onto an rb30 the reason i ask is i want a turbo but insurance would cost too much for me i was wondering how this would compare (obviously not as much potential power i guess or is there?)

Im doing this conversion too, although mines turbo. But no you dont have to run a turbo to do an RB25 head swap, it creates heaps more power & torque with an N/A unit. It is a relatively straight forward job cause all the dowles and oil holes line up, but some things do need changing. You ned a new timing belt cause the run length is increased. Reposition the RB30 tensioner. You need a new idler pulley. Exhaust flanges are different, need new or re-worked extractors. New throttle cable. There is some other stuff too, that I have forgotten. sorry ops: Most important you will need to get the RB25 computer or an aftermarket one cause there is no provision for a distributor with the 25, it runs a multi coil setup. If you use the 25 ecu, youwill have to get the 25 computer to plug into the VL's wiring loom, fun fun fun. 8O There is a Zoom article from somewhere that details this conversion for an N/A R31 skyline and I think the end result was about a 30% power increase (n/a) cause it flows better and revs more. Insurance, mate thats up to your insurance company, just call and ask them before ou do any work. Check with your local Transport Authority too incase you need an engineers report - dont know why but you never know. Cost of conversion, no idea either. I got my RB25 head with full port job and hi-po valves, springs etc for $1,000, but then again it was off my mate and he needed the cash fast. I've seen em at a import wreckers up here in Brisbane for $1200 (head). Just call around different workshops I suppose. Long post I know but I hope this helps. Cheers. 8) Some original photos have not been recovered yet.

ok sounds good did u mean approx 30% power increase without a turbo thast sounds pretty good.

Ok, just found the zoom article. Its in the Zoom Extreme Performance issue, green cover with a white R33 GTR and George Haddads orange 1000hp VN on the front. It says that it is a 32% power increase on a standard n/a motor. Between 100kw and 110kw at the wheels. If you do the conversion and add mods like sports exhaust, cold air & filter, new cams or even just playing around with adjustable timing gears on the cams, your car will haul ass. Let me know how it goes ok. Later.

sounds good i wont be dont this for a while though till i get the time and cash to do it but yeah sounds pretty good i mean about 32% increase then exhaust and everything should be a pretty sweet conversion.

Quote: Originally Posted by PSI 86 . Exhaust flanges are different, need new or re-worked extractors. rb20's exhaust manifold should bolt up Some original photos have not been recovered yet.

Ken oath. That power guess sounds on the money but what will really blow you away is the increase in the revvability of your motor. Ignore the 5500 redline and you should be peakin at about 7000rpm, once it gets over 5000 in 2nd it will pin you to your seat. Why don't you look at getting an updated cam when you do the conversion too, to see if you can improve upon the rb25de cam which is all top end, they lack a bit of torque before 3500rpm, then again maybe 500 mls will compensate for that. One thing I gotta note is that most fast vl turbos still only run single cam heads, imagine running a t04 with 22psi and forgies with a twin cam head. You should theoretically have an advantage or are there advantages to the SOHC when it comes to big horsepower?

where is a good place to start looking for the twin cam head, and any thing else you need to convert the rb30 with the 25 head?? places, phone numbers, web sites any thing would be good

Could u PLEASE scan the article of that head conversion? lotsa ppl would be interested and it would stop ppl having to always ask about it.

Quote: Originally Posted by dans Could u PLEASE scan the article of that head conversion? lotsa ppl would be interested and it would stop ppl having to always ask about it. There is an interesting article over at www.meggala.com , there is a part list from memory with everything you need to fo.

Quote: Originally Posted by dans Could u PLEASE scan the article of that head conversion? Id love to scan it mate but I dont have a scanner and I dont know anyone with one either. Sorry. If I get a chance to then I will though.

Quote: Originally Posted by PSICHO where is a good place to start looking for the twin cam head, and any thing else you need to convert the rb30 with the 25 head?? places, phone numbers, web sites any thing would be good Depends on which city you live in. if you are in Brisbane I can point you to a great import wrecking yard that has great pricing and service. They'll even seperate an RB26 top end from the bootom end and sell it seperately for you, try getting anywhere wlse to do that!! If not, just scan the phone books or mags like Zoom and call around Jap import wreckers. Cheers.

The following is an extract from an Autospeed article entitled "Head Start". "NISSAN Conversion: DOHC 24 valve RB25/RB26 head onto RB30 block Benefits: Replaces the narrow angle 2 valve SOHC head with a DOHC 4 valve head with larger valves, ports and intake runners. The RB26 uses six throttle body induction also. Please note: this is NOT an easy conversion and only the RB25DE or RB26DE head gives worthwhile power gains over standard. The RB20DE head CAN be fitted to the RB30 block, but if you're chasing more power from an already modified engine, the 2 litre engine's small ports and valves impose a gas restriction over around 4000rpm. It also requires enlargement of combustion chambers, and the welding-up of water galleries which are then required to be moved 5mm outward from the bore. Mods Required: First up, an RB25 belt cannot be used in this swap. A Gates belt or one from a belt supplier needs to be sourced. The readily available RB30 head gasket is able to be used. The RB25 twin cam head's variable inlet cam timing can be retained on the RB30 block by teeing off the oil pressure galley on the head and feeding the standard RB25 piston mechanism. This pushes the camshaft through a full 10 degree advance. All oil and coolant galleries mate up perfectly, with the exception of this cam advance unit. Programmable fuel and ignition control is needed to run the multiple coils of the RB25/26 as well as supplying to the different fuel requirements of the new hybrid engine. The RB26 also requires modification of car's existing throttle linkages to mate to the engine's six throttle body induction system. Note that at an approximate cost of $10-12,000, this conversion is certainly not cheap!!! Contacts: Nizpro Melbourne, Australia +61 3 9761 1522 Turbo Tune Adelaide, Australia +61 8 8297 1030 Peter Hill Auto Parts Kyabram, Victoria, Australia +61 3 585 23479 "

call me i can let u in on all the secrets all the do and donts i ended up useing a whole rb25det engine nigel [phone removed]

njpraw, whats the total cost on the full rb25det conversion??

it owes me about $2000 i sold my old engine for 1500 so really 3500 and i fitted it myself made exhaust and croosmember and console and dash i basicly did everthing myself ,i would reccomend this conversion to anyone

Quote: Originally Posted by njpraw it owes me about $2000 i sold my old engine for 1500 so really 3500 and i fitted it myself made exhaust and croosmember and console and dash i basicly did everthing myself ,i would reccomend this conversion to anyone so most of that price above ($10-12,000) is labour?

njpraw, whats your trade or job?

Christ its not that bad! Add it up - Head - $1000 (I paid $700 AFTER mods) I have hear $500 Belt $100 tops Tensioner $30 Manifolds $100-$300 should be with head but Head gasket $45 monotorque Computer $150 (I know someone who is selling one) Tuning $200-400 So at the top end, $2000 If you use your head and ask around you can do it cheaper. Do things yourself. Its not all that hard. I did it with EMS tuned for $2700 with NO contacts. Whoever said 10-12k is a numbskull. For that price you could have it done with a turbo, worked top end, aftermarket ECU, a nice set of wheels and paint too! You can use a non VVT head and it bolts on. Do what I did and get a VVT head? No dramas. Pay someone $90 to weld up a coolant hole partiall, weld up the VVt oil ffed and re-drill oil galleries for oil feed to cam main bearing. Simple. Use adjustable cam gears to fix the VVT module or make your own adapter. None of this T-piece ****. Some people do things the hard way every time. Rb20s have a different bore (78mm I think compared to 86mm for the res) so its an absolute joke if someone does that. What a waste of engineering on Nissans behalf. Don't use their inferior-bore technology on something that requires bigger hardware. Read up on the topic, get some prices, do as much as possible yourself, and you will have fun and learn heaps along the way. Satisfaction plus! Luke

hey VL boys here's a site with a Twin cam turbo conversion which was then dropped in2 a Shelby Cobra race car. It has a step through gide, pics and everything Im not sure if the site is still up but here's the address, it doesn't seem to work on my comp anymore. http://members.saonline.com.au/~rowan/twincam.htm Let me know if it works for you guys