NA mods for VH41DE

[Mettler]

Firstly, why is there no VH engine series forum ? We need one so that we can document what mods we do and what's good for what.

I don't really know of any definitive experts in modifying this engine, it's time the information became easy public domain knowledge so more people can tickle this motor up !

I intend to drop SR20DET 370cc injectors into my fuel rail, they should be a straight swap as the VH41DE appears to use the same style of side fed injectors.

With this increase in injection capacity, I will have my cams reground with a much, MUCH more aggressive profile, to give the engine that hearty lumpy idle and the awesome roaring race power that they can make.

Along with these proposed mods I'll already have a custom stainless steel intake with water misting in the cold air box, and custom extractors... my V8 conversion necessitates these.

To bring the above combination of upgrades together, I am looking into remapping the factory ECU through the use of a romulator device, once my ECU's mainboard is socketed. Depending on how much info I can find out regarding this, I may take the easy option and just run an aftermarket computer.

I expect that with these mods, I should have around 400-450HP at the flywheel.

I'd like your comments and tips please people

[elwesso]

If your using an OBDII VH41 you wont be able to reflash the ECU... They use this goofy programmable microprocessor (unlke most other ECU which use EEPROMs)...

i thought the VH's already had the 370CCs... I know the VH45 has the 370's, i thought maybe the 41 would have them too!

[Mettler]

Ah no ****, I never even knew the motor had 370cc injectors, I had assumed they would be lesser capacity, since it's only the SR20DET with that size and the VH is practically two SR20DEs with higher compression. I figured they'd be closer to 200something.

elwesso, how do you know so much about the VH engines ? I'd love to know the source of your info ! What's an OBDII VH41 ?

I'll assume you mean the second generation of VH41... mine came out of a JDM Y32 Cima, I'm pretty sure those are first generation.

Got a linky to any info regarding the ECUs on the VH engines ? I've searched these forums top to bottom, as well as google, and turned up nothing !

[elwesso]

Unfortunately, i cannot verify for sure that the VH41 has the 370s, but I know the 45 does...!!! So i suppose worst case you can pick up some 45 injectors and be done with it... Or like you said with the DeT injectors.. Hell, you could go with the NISMO 555s if you wanted!

Since your 41 came from a Y32, its gonna be OBDI which is good. Over here we only got the 41s with OBDII.. OBDII was used in the states as a standard OBD (on board diagnostics) manditory after 1995. ALL cars in 1996 had to have it, but some 1995s had them (not the Q though)..... I bet the 41 ECU is very similar to the 45 ECU in how it works. You sound like you know what your doing there, so its gonna be like doing a Z32 ECU or something similar... EEPROM no biggie.

I dont have a source of information besides my brain, theres no one definitive site for info on the VH series engines, besides right here on NICO.

[Mettler]

Cheers wes, be prepared to have your brain picked plenty then

Are you an infiniti mechanic, or just a learned enthusiast ?

I'd like to find out just what's different between the VH45DE and VH41DE (first gen motors), apart from the 45 having siamesed ports and the 41 having decent chain guides.

If that's really the only difference, then I'd feel a lot more confident referring to your Q45 information.

I did use a Q45/VH45DE engine wiring diagram to cull my loom back afterall... it was much the same apart from the wire colours being different, and one or two different devices. Fortunately it showed a picture of the plug and a numbering system for each pin, which we followed to a T.

Very few people play with the JDM VH41DE, well... I've found very few who do anyway. I've teamed up with my mate who is a pro with the RB engines, and hopefully due to the similar architecture to the R33 engines, our combined knowledge should be enough to make great things happen with this engine !

[elwesso]

Basically the ONLY difference I know of between 41s and the 45s is a shorter stroke. Its basically the same internals and stuff like that... WHICH is why I think the injectors are probably the 370s!!!!!!!!!!! Same pistons, heads and stuff...

However, the VH41 (in the 97+ Q) used these crappy log type exhaust manifolds and the inferior intake manifold (not the spider like on the 45).. however ive sen pics of 41s from Y32s and it seems they use the spider intake manifold, not sure about the exhaust mani's though. Comparing a G50 VH45 to a Y33 VH41 is night and day with the engineering it seems. I mean, the VH45 exhaust manifolds almost look like shorty headers youd get for your 5.0 mustang or whatever!

Actually the later VH45s (94+) didnt have the siamesed ports and also had the upgraded chain guides. Also had a different design injector which seems to hold up a little better, especially to our crappy "coors light" gas!

[Mettler]

Thanks wes ! My factory exhaust runners are ghey as, having custom headers made up.

If you want to know a bit more about my VH41 for your own knowledge, check out this linky, it has some pics and info about my project car.

http://mettler.orcon.net.nz/fi...p.htm

Please note, I've replaced the Laurel bodyshell to an HR31 GTS-X coupe now, but it's the same engine bay and driveline so it'll all swap straight over _b

[elwesso]

Nice thread on there!!! Man those manifolds are goofy, but im glad tosee that the spider intake lives!

Anyway that ECU looks just like the G50/VH45 ecu! nearly identical!

When your holdin that flywheel and those rims you look like a kid in a candy store!!

[Mettler]

Hahah that spider manifold rules, it's one of the best factory NA manifolds I've ever seen for any motor, let alone a nice V8.

Candy alright mate To give you an idea just how much time and money I have invested in this project car, until pics arrive, here are some specs to drool over:

Drivetrain & suspension equipment:

VH41DE 4.1 all alloy Quad Cam 32 valve EFI VTC V8IMPUL tuned/chipped factory ECUCustom fabricated stainless cold air intake with water mistingCustom fabricated 4-2-1 headersDual exhausts, 3" first half, into resonators, into 2.1/2" second half, into mufflersAt least a 3 or 5 core radiator with twin thermal fans5 speed manual conversion, custom modified bellhousing to accept toyota W57 transmissionCustom mounted slave cylinder, unknown replacement master cylinderModified rocker cover for master cylinder clearanceCustom fabricated gearbox crossmemberCustom designed lightweight 7079 alloy flywheel with friction insert, >5kgXtreme heavy duty pressure plate, 1050kg clamping pressureXtreme ceramic brass button paddle clutch with sprung centerD2 36-way adjustable coilover suspensionS13 180sx front suspension conversion, lower arms etcCustom fabricated 6061-T6 aluminium rear suspension hat-converters (2 to 3 stud)Custom modified rear wishbones - suspension mounting point remade to suit D2 struts, no swage on leading edge of strut eye, so chamfer on lug taken outNolathane bushes all roundCustom fabricated solid aluminium rear crossmember bushesSolid engine mounts & diff mountCustom fabricated driveshaftR200 longnose mechanical LSDZ31 300ZX rear 5 stud hubsK-style S13 Silvia 5 stud front hubsR32 GTS-t Mspec front rotors, 280mmx30mm (to be replaced with slotted aftermarket items soon as the budget allows)R32 GTS-t Mspec 4 pot front calipersR33 GTS25t Mspec rear rotors, 297mmR33 GTS25t Mspec 2 pot rear calipersTo run ultimates for brake pads, and high quality dot4 brake fluidMitsi Colt brake booster to clear rocker covers, and GTS-t Mspec brake master cylinder18"x9.5" rear & 18"x8.5" front deepdish alloy wheels275x35x18 rears & 245x40x18 fronts, Goodyear Eagle F1 GSD-3s

Body & cosmetic changes:Full strip & sand, prime, and paint. A nice black with a deep midnight blue pearl is what I'm thinking.R31house front lip, side skirts, and rear skirt (maybe, definitely the front lip)R31house Fibreglass bonnet (maybe... the plenum of the V8 might not clear the bonnet so it could end up being a custom fibreglass hood buldge not unlike a muscle ToranaDespoilering the backTintsIce blue xenon bulbsCustom GTS-8 decal to be made up for boot lid, using the same design font as the GTS-X one (thinking maybe GTR-8 ?)Ripping out the hicas, it won't do anything with solid mounts anyway :p

The project's been 8 months in the build so far, and I only just changed to the GTS-X a few weeks ago due to the incredible opportunity at that price. Still some ways off finishing it, I've gotta get the GTS-X road complied, registered, then do the panel work to it & paint it, drop the engine & running gear into it, fit the brake booster (needs a small mod behind firewall for it to fit properly), mount up the suspension & tune it all up, then get road certification.

Only after that mission will it be finished... and then I'm gonna want the following:

Proposed mods afterwards:Front & Rear strut braces... the front will prob need to be custom to fit past the plenum, but rear will be an off the shelf item from somewhere I'm sure.Modify the back plate of the R200 diff to have intake and exit hoses, oil pump + cooler setup to ensure the diff oil is nice and chilly and I can do burnouts all day Same as above but for gearbox... this may be a little harder, will look into it when the time comes.One of three options here... Cam regrind, SR20DET 370cc injectors & ECU retune for around 450HP & strong powerband OR.......VH41DETT, run twin T3 hybrid turbs on it with mild boost to get around 550-600HP, massive power... OR......VH41DES, run a belt driven centrifugal supercharger... the easiest way to get boost for this without fabricating too much ****e. It'll sound awesome too !

[Ezekial]

put sard 850 cc injectors in it and turbo or twin turbo it ... and push 500-550 rwhp with ease

[Nyloc]

Please note, I've replaced the Laurel bodyshell to an HR31 GTS-X coupe now, but it's the same engine bay and driveline so it'll all swap straight over _b

Thank goodness! That will be bloody cool!

I know a local man who has built dozens of VH41DE's, but its his livelihood and income so he rarely gives away a lot of info for free. But his engines are generally good for 600HP with a 4 barrel carb and headers on avgas, so there plenty of potential there. Its hard to find a top level stockcar that doesnt have a vh41de now, and those use the 1uzfe.
Modified by Nyloc at 2:12 PM 5/13/2006

[John Dixon]

T

put sard 850 cc injectors in it and turbo or twin turbo it ... and push 500-550 rwhp with ease

The Sard's are very expensive!Nismo 555's will give you plenty headroom on flow.Rough calc's based on 80% max duty cycle:

850cc max = 970bhp740cc max = 845bhp (nismo upgrade, common for 300ZX)555cc max = 630bhp (nismo upgrade, common for 300ZX)370cc max = 422bhp (stock)

[Ezekial]

The Sard's are very expensive!Nismo 555's will give you plenty headroom on flow.Rough calc's based on 80% max duty cycle:

850cc max = 970bhp740cc max = 845bhp (nismo upgrade, common for 300ZX)555cc max = 630bhp (nismo upgrade, common for 300ZX)370cc max = 422bhp (stock)

I dont $100 AUD (41 UK Pounds or $77 US) for a brand new injector is expensive ????

How much are the nismo injectors?

[John Dixon]

I dont $100 AUD (41 UK Pounds or $77 US) for a brand new injector is expensive ????

How much are the nismo injectors?

No, its not!! They cost way more than that over here!! Have only seen them as part of the border kit mind, it's about £1200 I think.Where are you sourcing those from?

[elwesso]

you can get them lightly used fairly cheap..... especially the 555s since the Z32 guys upgrade from them to the 740s.

[Ezekial]

No, its not!! They cost way more than that over here!! Have only seen them as part of the border kit mind, it's about £1200 I think.Where are you sourcing those from?

perhaps im stupid today but i cant seem to find how to PM you so i'll email you instead

[elwesso]

PMs are not on this board.. only email

[Mettler]

Hang on, what mods are you guys doing to require an injector upgrade ? I didn't think you'd need to bother unless you were going forced induction...

[Ezekial]

that was my suggestion.

actually ... just run a 200 shot of nitrous. its not as though the engine wont take it if the fuel delivery is correct

[Mettler]

I've looked into the costs associated with running boost in these engines... and I think I'll stick with a 400HP NA street thumper. I'm at the end of spending money on this project, reached a nice balance aye... any more grunt and I'll start needing to reinforce the chassis, rebuild the engine, use a bigger & stronger gearbox etc.