most desireable vh45de

[slownslurious]

I am going to be purchasing a used vh45de and using aftermarket engine management so limitations of electronics are of no concern. I will be keeping the stock bottomend and boosting to no more than 7 psi. What engine is the most desireable? I have heard the older engines are better as compression may be slightly lower but if all else was equal, I think I'd rather have the newest, lowest mileage engine to start my project with. As far as mounts etc are they all the same through the 90's?Does anyone have a link or anything to a chart detailing the changes that the motor underwent through the years? I found bits and pieces about intake man. changes, changes in compression, and the obd-II's lack of vvt...

[irax]

get non-vvt for best turbo results

[Mettler]

I've tried to go through this exercise but it seems like I'm the only one that's interested in the evolution of the VH engine.

So far, I've found the Y32 Cima ('91-'94) JDM spec VH41DE to be the best from factory, but I believe the '94-'96 VH45DE may share the improvements found in the Y32 engine... and I think the '96 version lost the VVT, perfect for the turbo application.

[elwesso]

OTher than the chain guides (which arent THAT expensive and easy to replace once the motor is out) the early (89-93) VH45s are just fine..... The injectors can be iffy but likely theyre OK if its from japan.

[Ezekial]

7psi at the most ... any reason WHY?

i like your post. aftermarket ecu. SMART MAN!!

ok if you are in fact only going to run 7psi and will have good ecu control ... DEFINATELY go for the biggest capacity engine possible. As 7psi is SFA. Also get the VVT engine as this will beef up your midrange and off boost power considerably. Once again you will need a good ecu to make the most of the advantages of VVT.

As wes said ... go the 89-93 VH45DE. Replace the chain guides (easy job) ... injectors wont be an issue for you anyway since you can run whatever injectors you like with an aftermarket ecu.

[slownslurious]

yeah I'd like to just get it running stock block stock injectors etc and see what its capable of. the most important thing for me is a lot of area under the torque curve and reliability. As far as jdm versus us spec motors go, are there any noteworthy differences or things to look out for? if I get an engine locally I have a pretty wide range to choose from and I could get any accessories etc that I might need, but the ones from japan seem to generally have lower miles or be a bit newer for around the same price. I think the vvt system would probably be just that much more complicated to tune. from what I am hearing it sounds like the 96 (and also 95 I think) with obdII and novvti would be a good choice... but what about japanese motors?

[Ezekial]

Quote »I think the vvt system would probably be just that much more complicated to tune. from what I am hearing it sounds like the 96 (and also 95 I think) with obdII and novvti would be a good choice... but what about japanese motors?[/quote]What aftermarket ecu do you have in mind?

I know Microtech can control it either switched via RPM off on off ... or off on.

If you are thinking of Motec you can run a 3D or 4D map to control it. Using parameters such as Manifold pressure, RPM, Engine Load, TPS, etc

[elwesso]

The VVT on the VH isnt really hard to tune at all... Hell, you can wire up a switch to the solenoids and then flip it on whenever you want

For 7lbs of boost (well within the capabilities of the factory injectors) why not just reflash the stock ECU... No extra wiring and very little tuning..... That ezekial guy, hes a real character The VVT system isnt very complicated, its either ON or OFF...

The VVT motors have more desireable cams for boost (with slightly more duration if memory serves), so if you dont want the VVT, just short the solenoids so they stay in the more wide open position (or the ON position)...

[slownslurious]

I want to go megasquirt, and I don't want to deal with the factory electronics cause the whole thing is going into my s13 (its my 3rd motor) and I'm just tired of fiddling around with the factory stuff trying to get it to do what I want to.

[Mettler]

Jap spec motors use consult, american motors use OBDII.

With consult, you can just plug a serial adaptor into the consult plug then run it into a laptop and get readings from there. I don't know how OBDII works so I can't comment on it.

Also, the main use of the factory VVT system is to keep the exhaust cam retarded during startup and early revs to make the engine easier to start and more efficient down low, then at higher RPM it advances the exhaust cam to get more top end power. It's a single on/off thing as Wes said, and isn't difficult to set up.

Me & my mate were tuning a factory ECU last night on his laptop, using a romulator. It was easy, and we were changing boost settings, fuel mapping, ignition mapping, you can reconfigure your AFM's values, run two AFMs etc... there's plenty you can do. I don't think aftermarket ECU is required at all until you run a MAP sensor.

If you want to build the ultimate VH45, use a Y32 VH41DE as a base, and install the VH45 crank and rods into it.

[Ezekial]

Also, the main use of the factory VVT system is to keep the exhaust cam retarded during startup and early revs to make the engine easier to start and more efficient down low, then at higher RPM it advances the exhaust cam to get more top end power. It's a single on/off thing as Wes said, and isn't difficult to set up.

how does it do anything to the exhaust cam?

[Mettler]

Well that's where the black VTC solenoid is mounted, you telling me it works the intake cam ?

Look on this pic:

[Ezekial]

The VVT on the VH isnt really hard to tune at all... Hell, you can wire up a switch to the solenoids and then flip it on whenever you want

For 7lbs of boost (well within the capabilities of the factory injectors) why not just reflash the stock ECU... No extra wiring and very little tuning..... That ezekial guy, hes a real character The VVT system isnt very complicated, its either ON or OFF...

The VVT motors have more desireable cams for boost (with slightly more duration if memory serves), so if you dont want the VVT, just short the solenoids so they stay in the more wide open position (or the ON position)...

I thought duration stays at 248?? Just inlet and closing angles change??

And isnt it the reverse?? off is open at 0 and on is open at 20 BTDC ?? In which case why wouldnt you want a 3D map to control it so you could turn it on to aid spool up, power off boost etc and then turn it off (closing at 68 ABDC) once you get to say 15psi to give you that extra margin for more boost??

[Ezekial]

pardon??

intake cam and intake cam as far as i can see

see pic

[Rex]

A couple thoughts from the outside (non-big hp tuning guy)

Late 89/early 90 VH45DE's were the strongest motors ... that doesn't mean they'd be best for boost, but they were the strongest of the VH45DE's. They used sodium filled valves which were dropped in late 93/early 94.

[defrag010]

not sure on this because I haven't taken apart a 93+ head, but SBI sells replacement exhaust valves that are sodium filled.. so depending on the size of the guide bosses in the 93+ heads, you could order some sodium valves and guides to put into your 93+ heads

[slownslurious]

I'm not really interested in building the strongest possible motor from all available parts, appealing as that may be, I'd rather not have to crack into the short block, and for my modest goals I'm relatively sure that I shouldn't have to. Can someone send me some info on this romulator stuff everyone is talking about? I want to look into it, but the thing is I really hate MAFS based systems even though I recognize that they do have strengths, they also have weaknesses, and my experience has been that they give off false readings as airflow increases, and that they can be difficult to adapt to different piping as it may cause their readings to be off thus affecting performance.

[elwesso]

The thing with the Q MAF is its so big and its VERY accurate at high flow rates... probably not the case with smaller MAF.

Anyway, ezekial, you're probably right..... My nomenclature is most likely at fault.... On the VH45 its definitely on the intake cam, MAYBE its different on the VH41 (i kinda doubt it)

I dont see why the VH41 block is any better than the VH45s, other than the guides...

The point of VVT is at low RPMs (below around 4800, dont quote me there though) is to let less air in, and at high RPMs to allow more to come in, to get better low end torque.

[Mettler]

I must be mistaken then Ezekial, I was under the impression the black control unit on the exhaust side is what controls the cam.

I dont see why the VH41 block is any better than the VH45s, other than the guides...

Nah I wasn't saying the block is better. It's not necessary either way, but it would be cool to combine the best features of all versions.

One definite benefit to using a VH41 is having the alternator at the top front of the motor. This will make chassis rail clearance easier... and for RHD cars, having the starter motor on the other side also helps to clear the steering column... but if slownslurious is from a predominantly LHD car country then this is not an issue.

If you want more information regarding ECU tuning, I highly recommend reading this page:http://cherrypicker.tripod.com/id10.html

I realise the article pertains to the VG30 engine, but the ECU works the same way as other Nissan ECUs. I have bin & address files to suit the VH45 engine, and you can socket & romulate the ECU to tune it how you want ! Can do it to RBs, SRs, VG, VH etc, any Nissan ECU to use the 28 pin eeprom setup !

The gear to do it will cost you less than US$400 too

[defrag010]

that little black attatchment onto the odd side exhaust cam is the CAS.

mettler, do you know if the VH41 accessory system will bolt onto a VH45 block?

[Ezekial]

The thing with the Q MAF is its so big and its VERY accurate at high flow rates... probably not the case with smaller MAF.

Anyway, ezekial, you're probably right..... My nomenclature is most likely at fault.... On the VH45 its definitely on the intake cam, MAYBE its different on the VH41 (i kinda doubt it)

I dont see why the VH41 block is any better than the VH45s, other than the guides...

The point of VVT is at low RPMs (below around 4800, dont quote me there though) is to let less air in, and at high RPMs to allow more to come in, to get better low end torque.

i think the way it operates is VVT OFF at idle = open at 0 close at 68 ABDC. Less overlap, increased LSA = smoother idle.

Then VVT turns on at like 1500 rpm. open shifts to 20 BTDC and closing at 48 ABDC. Increase overlap, decrease LSA = makes torque peaky, gives alot stronger midrange, shifts peak RPM up through the rev range

Then VVT turns off just after peak torque. Back to less overlap, increased LSA which at high rpm will help flatten the torque curve out and try to sustain the peak hp

See the 3D map can help you make use of this further but adding variables like i said. Manifold pressure, TPS, etc

Mettler ... alternator at the top is an advantage in a RHD car yes. Except it looks like a rotary = yukky

[Mettler]

that little black attatchment onto the odd side exhaust cam is the CAS.

mettler, do you know if the VH41 accessory system will bolt onto a VH45 block?

Ah true, thanks for clearing that up !

Nah I don't, I haven't had the chance to have a good look at a VH45 yet. But perhaps you could use that front photo I attached above as reference to figure this out ?

[slownslurious]

hmm... see the thing is, when I get my motor if I get the harness and ecu with it I'm going to have to pay for it (or if I import a jdm one it may not be availabl at all) and I know I can get megasquirt and make my own harness for around $400...so unlike you guys where you can do it for $400 I'm going to have that cost PLUS the cost of the ECU and harness, when for the same price I could have the megasquirt standalone... if that makes my decision a little clearer.From what I've been told here and by others it seems like a pre 94 block would be a good choice....this would work out well for me since it will be cheaper as well. I'm just worried because the motors I am seeing have around 100,000 miles on them for those early engines and I was hoping to get one a bit fresher.

[Mettler]

I wouldn't be so worried about the mileage... it's nice to get a fresher motor, but remember it comes out of a luxury car that was probably nana'ed for the most part. It's still a relatively unknown performance engine for the most part, in one of the most conservative styles of car.

[elwesso]

if you can before you pay for the motor, take the valve cover off the passenger side and look at the head, and it should be fairly clean. Will help you determine the oil changes.

[slownslurious]

I wouldn't be so worried about the mileage... it's nice to get a fresher motor, but remember it comes out of a luxury car that was probably nana'ed for the most part. It's still a relatively unknown performance engine for the most part, in one of the most conservative styles of car.

I know 2 guys that have them, one drifts his, the other beat a c5 corvette at the autocross last weekend.

lolI don't think any "style" of car is immune to abuse...