VK45 Pistons in a VQ30 engine = 11.x:1 compression ratio
01-09-2008, 09:59 PM
#1
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VK45 Pistons in a VQ30 engine = 11.x:1 compression ratio
OK here is another potential engine mod for those strange few of us who want to get more power out of a VQ30. 
Im just posting this as research but don't expect me to do this anytime. Im still cobbling other ideas on a VQ30 build up. I just wanted to post this to get some feedback on this idea. Think of the SR20 guys who use N/A Z32 VG pistons to get a high comp SR20 piston.
Anyways I saw this a few weeks ago.
http://forums.nicoclub.com/zerothread/179262
They took apart the VH45 block and took measurements on the parts. They said the compression height of the VH45 piston is 32 mm and that the block height is the same as the VK45. I verifed this in the FSM on the old Q45 and took a chance.
So I bought me one of these.
VK45 Piston.
I eyeballed the compression height with my measuring caliper and the compression height indeed appears to be 32 mm. This is 1.3 mm more than the VQ30 compression height (30.7 mm for those not paying attention). So if the VK45 piston was a flat top it would equate to around 11.7:1 static compression. But as you can see they have dished reliefs for the valves and a 1 mm raised area around the center of the piston. So my guess on the final static ratio will be around 11.2~11.5.
Now that the piston will stick 1.3 mm above top deck we have to worry about the valves hitting the pistons. However the reliefs are around 2.5 mm at their deepest point, almost double than the increased height of the piston. Also the VK45 and VQ30 heads have similar dimensions and geometery so the reliefs are in the right spots. The skirts appear to be shorter than the VQ30 pistons so there should be no piston/crankshaft/oil pan interference at BDC. I could be wrong but these feel a little lighter than a VQ30 piston as well.
I need to dig the old VQ30 pistons out of my shed to make some side by side measurements before I can say anything conclusive.
The only problem I see is that the upper ring land will be closer to the top deck and this may cause some issues. As far as anything else feel free to post.
So lets review.
Pros -
- Relatively cheap and readily available high comp piston for a VQ30, around $500 for 6 of them.
- Piston dimensions and tolerances are the same, so no need to bore and hone a VQ30 block to make these fit.
- Nissan/Infiniti goodness to make another 8~16 WHP for us VQ30 guys.
Cons -
- Upper ring land will sit closer to top deck and could cause some issues.
- Engine will always need high octane fuel, no more 87 octane safety net.
- Timing may have to be retarded in order to run these pistons unless other detonation reduction methods are used.
Discuss.
Im just posting this as research but don't expect me to do this anytime. Im still cobbling other ideas on a VQ30 build up. I just wanted to post this to get some feedback on this idea. Think of the SR20 guys who use N/A Z32 VG pistons to get a high comp SR20 piston.
Anyways I saw this a few weeks ago.
http://forums.nicoclub.com/zerothread/179262
They took apart the VH45 block and took measurements on the parts. They said the compression height of the VH45 piston is 32 mm and that the block height is the same as the VK45. I verifed this in the FSM on the old Q45 and took a chance.
So I bought me one of these.
VK45 Piston.
I eyeballed the compression height with my measuring caliper and the compression height indeed appears to be 32 mm. This is 1.3 mm more than the VQ30 compression height (30.7 mm for those not paying attention). So if the VK45 piston was a flat top it would equate to around 11.7:1 static compression. But as you can see they have dished reliefs for the valves and a 1 mm raised area around the center of the piston. So my guess on the final static ratio will be around 11.2~11.5.
Now that the piston will stick 1.3 mm above top deck we have to worry about the valves hitting the pistons. However the reliefs are around 2.5 mm at their deepest point, almost double than the increased height of the piston. Also the VK45 and VQ30 heads have similar dimensions and geometery so the reliefs are in the right spots. The skirts appear to be shorter than the VQ30 pistons so there should be no piston/crankshaft/oil pan interference at BDC. I could be wrong but these feel a little lighter than a VQ30 piston as well.
I need to dig the old VQ30 pistons out of my shed to make some side by side measurements before I can say anything conclusive.
The only problem I see is that the upper ring land will be closer to the top deck and this may cause some issues. As far as anything else feel free to post.
So lets review.
Pros -
- Relatively cheap and readily available high comp piston for a VQ30, around $500 for 6 of them.
- Piston dimensions and tolerances are the same, so no need to bore and hone a VQ30 block to make these fit.
- Nissan/Infiniti goodness to make another 8~16 WHP for us VQ30 guys.
Cons -
- Upper ring land will sit closer to top deck and could cause some issues.
- Engine will always need high octane fuel, no more 87 octane safety net.
- Timing may have to be retarded in order to run these pistons unless other detonation reduction methods are used.
Discuss.
Last edited by 98SEBlackMax; 01-09-2008 at 10:10 PM.
01-09-2008, 10:40 PM
#2
my main concern would be knock but then again.....also what about piston to valve clearnece?? i also think a good port on the intake side should be had to maximize the compression bump and make the most power
01-09-2008, 11:25 PM
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One more negative thing I just thought of and measured out...
If the VK45 pistons are sitting 1.3 mm higher above top deck in a VQ30 block the pistons will need to have the edges flycut or you WILL smack the cylinder heads at TDC.
Neither VQ nor VK cylinder heads have a perfect 93 mm diameter hole for the the piston to travel up into. If you look at either cylinder head they have flat areas on top of and below each combustion chamber that is flush with the deck of the cylinder head. You would need to shave off the corresponding material on the VK45 piston or it will hit the head at TDC.
So much for this being a no machine shop job.
If the VK45 pistons are sitting 1.3 mm higher above top deck in a VQ30 block the pistons will need to have the edges flycut or you WILL smack the cylinder heads at TDC.
Neither VQ nor VK cylinder heads have a perfect 93 mm diameter hole for the the piston to travel up into. If you look at either cylinder head they have flat areas on top of and below each combustion chamber that is flush with the deck of the cylinder head. You would need to shave off the corresponding material on the VK45 piston or it will hit the head at TDC.
So much for this being a no machine shop job.
Last edited by 98SEBlackMax; 01-09-2008 at 11:40 PM.
01-10-2008, 01:40 AM
#5
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many honda's, including the s2000 run 11:1 or as much as 11.5:1 from the factory on premium octane pump gas....any higher though and timing retard or direct injection becomes necessary to run with pump gas...
01-10-2008, 07:34 AM
#6
One more negative thing I just thought of and measured out...
If the VK45 pistons are sitting 1.3 mm higher above top deck in a VQ30 block the pistons will need to have the edges flycut or you WILL smack the cylinder heads at TDC.
Neither VQ nor VK cylinder heads have a perfect 93 mm diameter hole for the the piston to travel up into. If you look at either cylinder head they have flat areas on top of and below each combustion chamber that is flush with the deck of the cylinder head. You would need to shave off the corresponding material on the VK45 piston or it will hit the head at TDC.
So much for this being a no machine shop job.
If the VK45 pistons are sitting 1.3 mm higher above top deck in a VQ30 block the pistons will need to have the edges flycut or you WILL smack the cylinder heads at TDC.
Neither VQ nor VK cylinder heads have a perfect 93 mm diameter hole for the the piston to travel up into. If you look at either cylinder head they have flat areas on top of and below each combustion chamber that is flush with the deck of the cylinder head. You would need to shave off the corresponding material on the VK45 piston or it will hit the head at TDC.
So much for this being a no machine shop job.
All that aside, if you're increasing compression by changing pistons it goes without saying a cam change should be made. How your tuning requirement wrt ignition timing would change (for a given octane) is largely dependent on the resultant dynamic compression, has almost nothing to do with the static compression, and the dynamic compression would be determined by the cam specs.
Interesting idea, but it may not be better compared to buying a ~$1000 piston set once you factor in all the extra machining required (and we don't know for sure if the piston reliefs are adequate with higher lift cams (around ~11mm or higher)).
Last edited by DandyMax; 01-11-2008 at 06:27 AM.
01-10-2008, 02:14 PM
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You people are confusing me with all these metrics. .051" is a lot taller compression height than one might think. I would fab a spacer or use a thicker head gasket before I cut the head. Dirt track 4-bangers do this all the time. That way you could always go back to stock if you want. Fly cuts on the pistons would effectively lower the compression and weaken the piston.
I don't personally think $500 for 6 pistons is cheap, but maybe comparitively speaking it probably is. I guess that's why bowtie engines are so popular. Any idea what a piston maker would charge for a custom set?
At this point, I don't know specifics for either of the engines but I plan to learn. I just recently realized (joining here) that '02 maxima's did in fact have two different engines.
I don't personally think $500 for 6 pistons is cheap, but maybe comparitively speaking it probably is. I guess that's why bowtie engines are so popular. Any idea what a piston maker would charge for a custom set?
At this point, I don't know specifics for either of the engines but I plan to learn. I just recently realized (joining here) that '02 maxima's did in fact have two different engines.
01-10-2008, 02:58 PM
#8
No they don't
01-10-2008, 07:35 PM
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But technically, the '00-'01 3.0's are called 5th gens (A33a)
and the 02-03 3.5's are called 5.5 gens (or A33b)
01-10-2008, 09:53 PM
#13
01-10-2008, 10:23 PM
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I know, shame on them...I was just thinking that people wouldn't be so quick to do crazy expensive things like custom pistons and raising compression just to squeeze out a little more power...we could all use a few more ponies, but it would have been nice if the vq30 still incorporated some more technology to gain a little more power...of course it's all in retrospect...
01-10-2008, 11:06 PM
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You people are confusing me with all these metrics. .051" is a lot taller compression height than one might think. I would fab a spacer or use a thicker head gasket before I cut the head. Dirt track 4-bangers do this all the time. That way you could always go back to stock if you want. Fly cuts on the pistons would effectively lower the compression and weaken the piston.
I don't personally think $500 for 6 pistons is cheap, but maybe comparitively speaking it probably is. I guess that's why bowtie engines are so popular. Any idea what a piston maker would charge for a custom set?
At this point, I don't know specifics for either of the engines but I plan to learn. I just recently realized (joining here) that '02 maxima's did in fact have two different engines.
I don't personally think $500 for 6 pistons is cheap, but maybe comparitively speaking it probably is. I guess that's why bowtie engines are so popular. Any idea what a piston maker would charge for a custom set?
At this point, I don't know specifics for either of the engines but I plan to learn. I just recently realized (joining here) that '02 maxima's did in fact have two different engines.
The whole idea behind this is to raise the compression ratio so there is no need to use a thicker head gasket or modify the cylinder heads in any way. Not to mention doing this on a V type DOHC engine will alter the cam timing between the two engine banks and would be a pain to correct.
I've read of engine projects that have used flycut pistons without any problems, so im willing to take that risk. Also im sure if I get a custom piston made it won't be 100% cast in the final shape. Im sure they will have to flycut or mill off some metal to match my specs.
Modification of the VK45 pistons should not alter the compression ratio to much because I am only machining the pistons to clear the quench pads on the cylinder heads. There will still be a good bump in compression provided the machine shop does a good job for me. The only problem I forsee is what this reshaped piston will have on the combustion and swirl process, but accurately predicting all that is something that is beyond the scope of this forum.
To answer Dandymax's question the cams will be a bit mild, im thinking JWT VQ30 S1 cams (or S2
, if they will let me have them) or the Ebay VQ35 S1 knockoffs. Reason to not go crazy on cams is obviously for these pistons and VQ30 heads don't flow much better past 0.400" (10.16 mm) lift. So there was a good reason I flow benched all those VQ heads last year. 
As far as cost goes we are not in a bowtie land so thats why I said it's relatively cheap.
I grew up in a Chevy household and I know what power they are capable of. An equivilant LSx build would easily give me twice the power for the same price. Bowtie economincs are pretty much out the window at this point...It would be $733.01 for the VK45 pistons and rings and about another $200~$400 to machine them to fit. Since they match the stock bores you can put these in the block and you won't even have to re-hone the cylinders. (All the VQs I've seen have maintained their factory hone marks past 50K miles.) Not to mention they have the moly skirt coating similar to Swaintech's and some other coatings around the rings, this would be extra on custom pistons.
So lets estimate over a $1000 for custom slugs and hope that includes the rings. Since they can't match the factory bore tolerances I would have them made to 93.5 mm for a 0.02" overbore. Now factor in the cost of making a proper TQ plate for boring, the bore & hone, and a redecking of the block to verify it's flat after all that maching. Im probally past $1500 at this point and I still have to get the skirts coated from Swaintech.
Either way it's not cheap but this can be a less expensive alternative to the custom piston route.
Im gonna let this thread stew for another day. over +12 hours of work doing optical and laser research takes a bit out of me. Then I come home to do some VQ research before bed, lol.
Last edited by 98SEBlackMax; 01-10-2008 at 11:13 PM.
01-11-2008, 03:49 AM
#16
The 5th gen did carry over untill 03 but they made some major changes in 02. My only point was that the engine was the same in all 02-03 models.
You said in 02 that there were 2 different engines and that isn't the case.
00-01= 3.0
02-03=3.5
Something you read was wrong and I just want to clarify.
Sorry to the OP! I've just been trying to learn off you and had to state some facts at the same time...
01-11-2008, 06:24 AM
#17
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Most of the piston companies want about $150.00 per hole and that includes rings and pin. Some of the companies want you to spec the piston and will not build to someone else's spec that they have built to before. For some reason they charge more for import motors than domestic motors. I had Arias build me a set of 11.5:1 pistons for a VQ35 and I could do it over the phone since they had made VQ35 pistons in the past.
01-11-2008, 06:32 AM
#18
To answer Dandymax's question the cams will be a bit mild, im thinking JWT VQ30 S1 cams (or S2 , if they will let me have them) or the Ebay VQ35 S1 knockoffs. Reason to not go crazy on cams is obviously for these pistons and VQ30 heads don't flow much better past 0.400" (10.16 mm) lift. So there was a good reason I flow benched all those VQ heads last year.
, if they will let me have them) or the Ebay VQ35 S1 knockoffs. Reason to not go crazy on cams is obviously for these pistons and VQ30 heads don't flow much better past 0.400" (10.16 mm) lift. So there was a good reason I flow benched all those VQ heads last year. 
...but good to see you'll be doing cams (I figured you would, but I posted anyway for whoever else might read). Do you have any decent engine modeling software? It can be quite useful... Not interested in doing any porting I take it?
Last edited by DandyMax; 01-11-2008 at 06:37 AM.
01-11-2008, 07:50 AM
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It's all in fun. I'm here to learn like everyone else. I'm just blown away being the car nut I am that I just found this site with its plethora of information. With these measurements and tolerances so close between engines, it could nearly be called a modular. Course if they stated that Joe's idea would have been discovered a long time ago and people would have saved a bundle. I'll admit it has been a long time since I have really been involved in any engine mods or builds. The lat car magazine I read was right around the time the 3.5 was introduced.
01-11-2008, 11:59 PM
#21
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It wasn't a question it was a suggestion... ...but good to see you'll be doing cams (I figured you would, but I posted anyway for whoever else might read). Do you have any decent engine modeling software? It can be quite useful...
Not interested in doing any porting I take it?
...but good to see you'll be doing cams (I figured you would, but I posted anyway for whoever else might read). Do you have any decent engine modeling software? It can be quite useful... Not interested in doing any porting I take it?
Im not looking to port these heads out as they flow pretty decent to begin with.
01-12-2008, 07:03 AM
#23
No problem, I left a message for the JDM folks, hopefully I'll hear back on Monday. Interesting thing, the VQ30DD pistons have different part #'s for each bank! Please re-send the PM, & I'll look into that too!
01-12-2008, 10:37 AM
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The different bank part #s could be a sign that the pistons have asymmetrical skirts, which would be nice.
Last edited by 98SEBlackMax; 01-12-2008 at 10:39 AM.
01-12-2008, 11:03 AM
#25
Yeah I've been using Dyno2000 to test out all these engine combos. Now that I have good flow bench data the software isn't so bad. With my current setup the software predicts 262 HP @ 6500 rpm / 257 TQ @ 4000 rpm at the crank. The HP is almost spot on but the TQ is a little higher than what I have.
Im not looking to port these heads out as they flow pretty decent to begin with.
Im not looking to port these heads out as they flow pretty decent to begin with.
So have you decided to go ahead with this project for sure?
01-12-2008, 11:34 AM
#26
Well there were four part #s for the VQ & VK pistons I ordered. Grade 0, 1, and 2 for stock bore sizes and another one for a .02" overbore. Im hoping they use the same grading system that the US engines use so I won't have to do an overbore.
The different bank part #s could be a sign that the pistons have asymmetrical skirts, which would be nice.
The different bank part #s could be a sign that the pistons have asymmetrical skirts, which would be nice.
I'm thinking it might be for fuel injector reliefs or something.BTW, nissan's service size is usually +.2mm.
01-12-2008, 05:25 PM
#28
For instance, here is a VQ35HR piston crown (Credit: SR20DEN)
http://www.turbo6.net/vqtech/Images/...0206071920.jpg
http://www.turbo6.net/vqtech/Images/...206071919d.jpg
Per the FSM the intake valve is larger by 6mm compared to the exhaust yet the reliefs are identical.
01-12-2008, 07:05 PM
#29
[QUOTE=nismology;6186939]It's alot cheaper to have all the pistons machined in the same manner and able to be installed on either side (valve reliefs the same size). None of the nissan V-block pistons have different part numbers for either side other than this direct-injected 3.0. Maybe there are others but they're are in the minority, for sure.
I've been looking at the VQ30DD parts catalog, and it's a weird motor- It has 6 intake ports per head, a really strange lower intake, a bizzare injector setup, and a cam-driven high-pressure fuel pump! It has timing covers like a revup or HR with VVT on both cams, but only the intake cams are variable. I guess if they're cheap enough, I'll order a couple of those pistons & see what I get!
I've been looking at the VQ30DD parts catalog, and it's a weird motor- It has 6 intake ports per head, a really strange lower intake, a bizzare injector setup, and a cam-driven high-pressure fuel pump! It has timing covers like a revup or HR with VVT on both cams, but only the intake cams are variable. I guess if they're cheap enough, I'll order a couple of those pistons & see what I get!
01-13-2008, 10:23 PM
#30
I recall SR20DET GTi-R pistons where only like 54 bux each back in the day and they came with new rings. I put a set into my SR when I was building a low compression motor for turbo duty.
Interesting info on the DD pistons.
I wonder how much extra power is there to be gained from port & polishing ? Dan do you have any figures ? I wouldn't mind getting a set of heads ported and polished. I got in touch with Dan Paramore Racing a while back but they never mailed me back.
Interesting info on the DD pistons.
I wonder how much extra power is there to be gained from port & polishing ? Dan do you have any figures ? I wouldn't mind getting a set of heads ported and polished. I got in touch with Dan Paramore Racing a while back but they never mailed me back.
01-19-2008, 09:38 AM
#32
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That's a good price for pistons.
Important thing to check with the VQ30DD pistons is the compression height and how deep the valve reliefs are, if any.
If I can manage the cold and snow to dig out some old VQ30DE pistons I could send one to you. Or you could send me one of those DD pistons your getting.
Also do you have any FSMs or data on this engine at all? You can usually figure out most of the important specs if you get a copy of the FSM.
01-19-2008, 10:08 AM
#33
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Not a whole lot IMO. Unless you want to goto an all out lightweight track car.
From my flow bench tests even the lowly VQ30 heads flow better than many OHV heads and some OHC heads.
For example if I plug the superior VQ35 flow data into Dyno2000 on a VQ30 engine it barely makes any changes to the power output. Granted there is more going on than just static flow #s, but the head builder I worked with said that either head will make decent power. The only work he would recomend for a streetable car would be to match the lower to the head, evenly rough up the lower/intake ports (golf ball dimple theory), clean up the bowl areas, polish the exhaust ports, and gasket match the exhaust ports and headers.
His opinion on other things that will make more power for VQ30s would be cams and reworking the intake manifold or going to a ITB setup. The problem with big cams is that we are flow limited around 11.0 ~ 11.5 mm and lift limited around 12 mm or so. Around that point the cam lobes will scrape into the head.
01-19-2008, 02:05 PM
#35
That's a good price for pistons.
Important thing to check with the VQ30DD pistons is the compression height and how deep the valve reliefs are, if any.
If I can manage the cold and snow to dig out some old VQ30DE pistons I could send one to you. Or you could send me one of those DD pistons your getting.
Also do you have any FSMs or data on this engine at all? You can usually figure out most of the important specs if you get a copy of the FSM.
02-02-2008, 03:19 PM
#37
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I am doing a vq30de buildup, and would need some high comp pistons. I am going to use E85 so I am looking for 13:1 in static compression.
Will probably use BC 272deg cams. And ITB's
Is there any company that sells aftermarket pistons? Otherwise I'll guess that using vk45 or VQ30DD and machining of the heads 1mm is the way to go.
DAVEB, Have you received the DD pistons yet? IF you like I can take any measurements that you need on my stock pistons.
Anyway, I am going to put the VQ in this car:
2001 Opel speedster, Mid-engine, 860kg
Picture of the engine bay, with the 2.2L I4 engine
Will probably use BC 272deg cams. And ITB's
Is there any company that sells aftermarket pistons? Otherwise I'll guess that using vk45 or VQ30DD and machining of the heads 1mm is the way to go.
DAVEB, Have you received the DD pistons yet? IF you like I can take any measurements that you need on my stock pistons.
Anyway, I am going to put the VQ in this car:
2001 Opel speedster, Mid-engine, 860kg
Picture of the engine bay, with the 2.2L I4 engine
02-02-2008, 04:45 PM
#39
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02-02-2008, 08:12 PM
#40
DAVEB, Have you received the DD pistons yet? IF you like I can take any measurements that you need on my stock pistons.
I haven't received them yet- Probably 2-3 more weeks. I did get a stock piston to measure, so I'm good there. It would be cool if someone could CC a stock combustion chamber.
I haven't received them yet- Probably 2-3 more weeks. I did get a stock piston to measure, so I'm good there. It would be cool if someone could CC a stock combustion chamber.