IceY2K1

iTrader: (3)

Can someone help calculate what the resulting compression ratio would be? Are there any more specifications that are needed to calculate this?

I've ran it through the calculator http://www.turbofast.com.au/TFcomp.html

I calculated a STOCK VQ35 Head Volume of 49.949 using Bore(3.760), Stroke(3.205), Deck Height(0.03), Gasket Thickness(0.04), and the Compression Ratio of 10.3. Then I used the Head Volume(49.949) and VQ30 Stroke(2.886) with the same Deck Height(0.03) and Gasket Thickness(0.04) to get the Compression Ratio of 9.37:1.

However, I think the Head Volume is NOT going to be the same as the stock VQ35, since the stroke has changed. Anyone agree/disagree?


From the ESM:

VQ30:
BorexStroke = 3.66x2.886in(93x73.3mm)
CR = 10.0

Piston:
Piston Face to wrist pin height = 1.787in

Connecting Rod:
Center Distance = 147.60-147.70mm/5.8110-5.8149in
Big End Inner Diameter = 48.000-48.013mm/1.8898-1.8903in

Crank:
Pin Journal Diameter = 44.968-44.974mm/1.7704-1.7706in
Center distance "r" = 36.61-36.69mm/1.4413-1.4445in

VQ35:
BorexStroke = 3.760x3.205in(95.5x81.4mm)
CR = 10.3

Piston:
Piston Face to wrist pin height = 1.614in

Connecting Rod:
Center Distance = 144.15-144.25mm/5.6752-5.6791in
Big End Inner Diameter = 55.000-55.013mm/2.1654-2.1659in

Crank:
Pin Journal Diameter = 51.968-51.974mm/2.0460-2.0462-in
Center distance "r" = 40.36-40.44mm/1.5890-1.5921in



The reason why I'm interested is because the small end of the connecting rod, piston pin, cylinder bore depth(3.94in), crank center-line to cylinder block face(8.4665) on BOTH the VQ30 and VQ35 are the SAME. Plus, the main journal diameters are the same!!! So, the VQ30 crank AND rods *SHOULD* swap into a VQ35, while keeping OEM or aftermarket VQ35 pistons. HOWEVER, the biggest "Oh Sheit" I can see is the VQ30s' smaller crank center distance "r"(1.4413in vs. 1.5890) and VQ35s' smaller piston height(1.614in vs. 1.787in) not outweighing the VQ30s' connecting rods longer length(5.8110in vs. 5.6752in), which would cause a collision between the piston and valves at TDC. I don't know...need to think about it more later.

Anyways, hopefully the resulting CR is between 8.0-9.5:1.

s0ber

iTrader: (7)

wtf this is not for the faint of heart :P

Sprint

iTrader: (10)

why?

dmontzsta

he is just obsessed with stroking.

IceY2K1

iTrader: (3)

It's no more difficult then what Mardi is doing right now and probably Kev in the near future.

Mardi is using a VQ35 block, pistons, crank, ie bottom half of the VQ35 and bolting it to the top end of his VQ30. Same deal, except you RE-use the crank, rods, from the VQ30.

dmontzsta

simply put, not worth the money, go boost if you want more juice...NOS or custom turbo.

people usually bore and stroke up sizing. This would be a dumb investment.

s0ber

iTrader: (7)

man sprint, good look on what u doin :P We could all use that.. heh

IceY2K1

iTrader: (3)

What do you think I'm talking about lowering the compression for? Why do you think Mardi is SC+NOS, yet going with the VQ35 bottom-end for the .5L additional displacement.

The LIMIT on our motor is the CR. This *MIGHT* be a FREE solution to both, since we don't have cheap alternative LOW CR pistons available.

If you want to REAL levels of boost, not just 10-12psi max, while on 91-crap octane pump gas, then this *MIGHT* be a VERY cheap solution vs. having CUSTOM pistons made.

Basically, buy a VQ35 short block from a junk-yard, slap the VQ30 crank AND rods into it, and slap on the VQ30 heads.

Yes, this is ONLY for people who are planning on rebuilding anyways. However, Mardi can EASILY do this now.

dmontzsta

you wont say that right now.

atleast the 3rd gen has more class and recognition than a taurus, ooops I mean minima, or errr 4th gen.

SR20DEN

iTrader: (7)

95.5mm x 73.3mm = 3150.3 cc

You need to stop using that SAE crap.


Stock CR on a VQ35 is 10.3 to 1. Stock CR on a VQ30 is 10.0 to 1.

Swept volume on a VQ35 cylinder is 583.0704466cc

Swept volume on a VQ30 cylinder is 497.9208088cc

Total chamber plus head gasket volume on a VQ35 is 62.6957469

Total chamber plus head gasket volume on a VQ30 is
55.3244676

The VQ35 head gasket is about 3.58cc therefore the VQ35 head volume is about 59.1157cc


ughh... it's too early in the morning. I'll finsh this later.

MardiGrasMax

iTrader: (14)

Is the total chamber volume listed assuming that the pistons on both stock motors are flat top and even with the deck? FYI, They are not, VQ30 seem sorta dished, VQ35 are dome w/ valve reliefs. I dont know about the deck heights, will soon. Although this isnt rocket science, as you guys know, this needs to be right on. For instance JWT needs an exact CR to program my ECU for my turbo application, VQ35 short block w/VQ30 heads. I have all the other measurements needed except piston deck height. And since I dont have the pistons in the block I cant measure the volume of the piston at TDC, with out this info the calculations would be fudged. So I have to wait till I get the pistons in the block and CC them. FYI SGP's pistons are a -16cc dish, for just the piston top.

But if your gonna stay with stock rods and buy a junked VQ35, just get low CR pistons, for a few bucks more you get allot more performance, till you snap a rod or blow a head gasket. Although I think using ARP head studs will strenghten the headgasket seal enough that the stock rod will go first.

IceY2K1

iTrader: (3)

Hmmmmn...using a Deck Hight = 0.13(added 0.1 for change in stroke), Bore = 3.760, Stroke 2.886, Gasket Thickness = 0.40, YOUR head volume of 59.1157 the CR = 6.83:1. Too low for a street car.

IceY2K1

iTrader: (3)

It's based off my guess of Deck Height = 0.03, Gasket Thickness = 0.04, and Compression Ratio of 10.3, so I don't believe it matters what piston surface is like.

However, I NEED to know that for this to work also.

How much do SGPs' pistons cost?

This *IDEA* was using the VQ30 rods AND crank with the VQ35 pistons and wrist pins. I agree keeping the whole 3.5L of displacement would be MUCH more attractive then the resulting 3.15L.

Low CR pistons are available for the VQ35? Top Secret supposedly makes some, but I haven't seen any YET for the VQ35.

IceY2K1

iTrader: (3)

I wonder if that's because the VQ30 intake valves are LONGER then the VQ35, however all the other dimensions appear to be the same EXCEPT the VQ35 valves are 1mm in diameter larger.

SR20DEN

iTrader: (7)

If the pistons are not flat top that go to zero deck height that makes it much more complex to determine the effective CR. My guess is that you will need custom pistons top make the thing work. And why do all this work for barely 3.2 liters when you can start with 3.5?

SR20DEN

iTrader: (7)

How in the world did you come up with a number that low? If we we're lucky and everything else was a direct drop in you could use the following equation (497.9208088 + 62.6957469)/62.6957469 = 8.94 to 1 . Although we know that isn't perfect, it's probably more realistic of the outcome.



Actually I forgot to include the new swept volume of the combo (525.049923). So that would be (525.049923 + 62.6957469)/62.6957469 = 9.37 to 1.

HitManSE

iTrader: (1)

Man its still too early, ill just kick back and Looks interesting...

tornado019

Hey this is pretty interesting. Swapping out between the vq30 and vq35. Lowering the compression ratio opens up more room for forced induction, isn't that correct?

I'm just curious though, can you go the other way? Put the vq35 crank in a vq30 to stroke it out to a larger displacement? I've been wanting to rebuild my vq30 and would love to stoke it out, just wasn't sure if it could be done.

SR20DEN

iTrader: (7)

Again, IMHO and at least one other unnamed person. Anyone who wants to do a VQ upgrade should just get a VQ35 long block and drop it in. I challenge any of you to find a worthy advantage to destroking a VQ35 or stroking a VQ30. Using a VQ35 long block is the most potent and cheapest way out.

HitManSE

iTrader: (1)

Most probably it is yes, but lets not start a "debate" on it and see were this thread leads. Usually after 3pages post notification isnt sent anymore. Just for the record Im with you on this one but like I said lets see what happens...

tornado019: That will most likey lead to piston to valve contact, if not piston to cylinderhead contact

Bags

iTrader: (3)

man you think like 1000 times more about this stuff than me.. I just was thinking about how I can get the neon rings around my wheels

Maximam

I would replace the pistons to lower the compression ratio. The question is what would the cost be?

IceY2K1

iTrader: (3)

Originally, my idea was to come up with a way to lower the CR withOUT big $$$ for custom low CR pistons. However, Mardi says they are available, so that's probably the better route. Another reason is that I wanted to keep the VQ30 Rod Ratio...VQ30 Rod Ratio is better then the VQ35, especially for turbo IMO.


Deck Height going from 0.03->0.13 is what caused it.

VQ30:
Piston = 1.787in
Con rod = 5.811in
Crank center distance = 1.441in

At TDC length = 1.787+5.811+1.441 = 9.039in

Swap in VQ35 Piston = 1.614in

At TDC length = 1.614+5.811+1.441 = 8.866in

So, if the Deck Height WAS 0.03, it IS 0.173in(9.039-8.866) now.

Actually, the CR is going to be even lower now that I've actually crunched the numbers and it appears the Deck Height should be 0.203. I'm LEARNING here SR20DEN, so take my numbers for what NEWBIE info they are. I'm still unclear on lots of terms.





I was right!?!?!?!

IceY2K1

iTrader: (3)

I'm NOT attempting to debate, which is BETTER. I'm simply looking for help on ANOTHER possibility. The more options people have the better. I just think it's FASCINATING that the small end of the con rod, wrist pin, and main journals are the SAME *possibly* allowing interchanging.

You can gain the 0.5L of displacement by dropping in a VQ35 long block, however withOUT low CR pistons, you're still limited on the amount of boost you can run on pump gas.

Then there is the Rod Ratio issue, which I don't care to hash out here, other then I prefer the VQ30 RR especially for a turbo. Now for a SC, the VQ35 RR may be better, I'm not sure.

SR20DEN

iTrader: (7)

Chill man Im not trying to flame. Im just throwing out more numbers and I said all of my stuff wasn't right since I left out so much. I just wanted to know your motives behind the question.

You really might try to do away with that SAE crap and do all the math in Metric instead of having to convert all the time. That goes for you too Mardigras.

SR20DEN

iTrader: (7)

I know you're not trying to debate, nor am I. And yes most of these parts are interchangeable as you stated. But I am curious as to why you think the rod ratio of the VQ30 is better than the VQ35? Granted the lower ratio on the VQ35 will make more low end torque and put more stress on the piston skirts but even it is still better than many other boosted engines.

VQ30 RR 2.0136 to 1
VQ35 RR 1.7708 to 1

A Chevy 350 RR 1.63793 to 1

IceY2K1

iTrader: (3)

I'm not looking for people to help figure out a "better" way, I'm just looking for help on IF this would be possible. Are there probably cheaper alternatives, better alternatives, practical alternatives, YES! I don't really care about all that right now, since I'm just brain-storming to SHAKE things up a bit and see what falls out. Brain-storming this *MIGHT* help Mardi or others who are planning on the VQ35 block + VQ30 top end.

Motives? Cheap way to run REAL boost levels on pump gas withOUT going with custom internals.

Sorry, I'm using an Aussie calculator and it only takes SAE.

SR20DEN

iTrader: (7)

Again yes it is possible. Cheaper? I wouldn't think so. Practical? A matter of opinion and mine says no. Shake things up? The only thing I have seen so far is other people getting confused by all the numbers and math. Help Mardi? He's always looking for new ideas and open to suggestions but in this case I think he's made up his mind.

Cheap way to run high boost levels? I don't think there really is such a thing as cheap in this case unless the stock motors can handle more than we give them credit for. If I had access to all of the data I could give you perfect calculations on the CR.

And just use your windows calculator for equations. Go to a local book store or amazon.com and get 'Auto Math' by John Lawlor. I recommend it to everyone who cares to know how to calculate all this stuff correctly.

IceY2K1

iTrader: (3)

Other then high-end breathing red-line peak power engines typically have a higher RR. So, I ***ume that's going to work better with a turbo, especially if you have a 7200rpm redline with a JWT ECU.

All THEORY and could be myths, but as I dig I learn, so I'm going to keep looking for sheit others haven't and see what falls out.

All this may be common knowledge to you and others like Mardi, but I haven't got a clue.

SR20DEN

iTrader: (7)

I am just trying to feed your fire here.

Food for thought:

A SR20 is a much higher revving motor than a VQ30 or VQ35 and has a longer stroke than both, 86mm vs 73.3mm or 81.4mm. It's rods are also shorter @ 136.6mm.

Therefore a high revving, high boosting SR has a RR of 1.588 which is much lower than the VQ35.

SR20DEN

iTrader: (7)

Good read.

http://www.sportcompactcarweb.com/te...scc_ssbbpart7/

IceY2K1

iTrader: (3)

How is it not cheaper? You have to buy a VQ35 from a junkyard anyways, then you toss the pistons for low CR ones. If this works, you don't need too. I say it's practical IF the parts are interchangeable and it lowers the CR to an acceptable boost friendly level. Otherwise, screw it and get low CR VQ35 pistons and keep the extra displacement. Did you know the pistons, wrist pins, rods, and crank were interchangeable? I didn't until recently. Mardi is just an example. There are others such as Kev still debating building up a VQ30 or VQ35.

If the swap is possible and the CR ends up 7.0-9.5 for the same cost as a VQ35 in the junkyard, then I'd say it's cheap compared to buying low CR pistons especially if they have to be custom made. I give the VQ30 crank and rods credit to 500whp. Lower the CR to run on 91-octane pump gas and we'll see what the rods can handle.

Thanks.

IceY2K1

iTrader: (3)

Interesting...I'll have to think about that.


Awesome...my subscription just ran out, so I missed that one. However, if I'm reading that correctly, the higher the RR the better for lower piston speeds and high-rpm performance, right? Wouldn't that suit a turbo VQ better?

Black VQ

I've thought about doing the same thing to a VQ35 block, trying to create a VQ32 or something. My idea was for NA purposes, however. The major roadblock others pointed out was the piston angle and possibility of cylinder wall wear...or something like that.

With a lower rod-stroke ratio and the higher revving available from the VQ30's shorter stroke, the pistons might reach speeds where they could begin to make contact with the cylinder walls.

I'm not sure if this would be a problem with your application(how many revs do you plan on?), but I figured it would be worth mentioning.

IceY2K1

iTrader: (3)

Correct me if I'm wrong, but I think it's the other way around. The higher the RR(longer rod), the lower the piston speed. Therefore, the VQ32 would allow more revs then a VQ35, but less then a VQ30. However, we know the VQ35 rev-limiter is 6600 vs. VQ30 6400, so that shouldn't be an issue.

VQ30 - 2:1
VQ32 - 1.81:1
VQ35 - 1.77:1

The only guys that have to worry about piston speed are the VQ30DE guys, since they have JWT ECUs w/7200rpm rev-limits. I'll never have that concern.

SR20DEN

iTrader: (7)

The RR really has nothing to do with the peak piston speed. It does have alot to do with the dwell and piston acceleration. The stroke determines the piston speed.


Piston speeds:

VQ30 @ 6500 RPM = 3126 fpm
VQ30 @ 7200 RPM = 3463 fpm
VQ35 @ 6550 RPM = 3498 fpm

IceY2K1

iTrader: (3)

Thanks.

VQ30 rev-limits at 6400 not 6500 though.

Black VQ

Okay, so if I hear you guys right...

A VQ35 with a VQ30's stroke, something like a VQ32, wouldn't have any cylinder wall wear problems as long as the rev limit was kept stock? I was just thinking that this type of motor, with its very oversquare design(stock bore VQ30 is already oversquare), would make for a sporty NA engine.

IceY2K1

iTrader: (3)

Rev limiter wouldn't be a concern unless you COULD stroke the VQ35.

If you're going NA, then I'd just go with the complete bottom-end VQ35.

If you going FI, then VQ32(VQ35 block/pistons w/VQ30 rods/crank) or VQ33(VQ30 block/pistons w/VQ35 rods/crank) might be possible for the cost of a junk-yard VQ35, which seems to be ~$850. Otherwise, just buy VQ30 or VQ35 low CR pistons, depending on what motor you have, and turn up the boost.

IceY2K1

iTrader: (3)

SGP 8.5:1 Forged VQ35 Pistons $1,320:

http://store.yahoo.com/sgpracing-sto...ra8fopise.html

SGP 11.5:1 Forged VQ35 Pistons $1,320:

http://store.yahoo.com/sgpracing-sto...ra11fopis.html


If you are sticking NA and have BIG $$$, go VQ35 bottom-end w/11.5:1 pistons.