OHC SBC's

I'm not sure if this is advanced enough for some of you guys so feel free to relocate this post.

I came upon a name the other day that some of you might know, Pete Aardema. Mr. Aardema has made a living building wild OHC motors out of previously pushrod blocks. Most notably attaching Porsche 928 DOHC heads to a BBC after realizing the bore centers were within .030".

Anyway, on his website you can buy an OHC kit.

http://www.aardemasohc.net/index_files/Page313.htm

Anybody have any experience with these? Any thoughts on advantages/disadvantages.

I know that GM sticks with pushrod engines for its racing motors for many reasons; lower center of gravity, lighter weight, simplicity of proven technology, etc.

Still, Aardema claims 7500rpm on stock valvesprings. I think this has some good application on smaller displacement motors (i.e. the beloved 302).

Your thoughts?

Jeremy

I have a 302ci SBC....a cammer mouse motor would be the ****

I actually just talked to Pete Aardema on the phone. He's a really cool guy. For what I want to do his kit would cost around $3000. But he also suggested I get some DOHC heads from an infinity/nissan. The bore centers are about .009" off an SBC.

Food for thought,

Jeremy

For what I want to do his kit would cost around $3000.

Can you tell us what he will provide for $3k?

Look at the link. I think he makes it out to be a little more simple than it really is, i'm not sure. It looks like an adapter to go on top of the heads. You actually send him your heads for fitment. 2 cams, of course. A belt and miscellaneous other pieces. The problems you might run into in the LT1 are your cam driven opti and water pump. The stock cam stays in the motor to run the oil pump, but the faceplate with all of the timing belt pulleys doesn't really look like it's meant for the LT1.

Still, for $3000 it doesn't seem like a bad deal if you just want something different. This guy loves different, he has a mid-engined Model A hotrod.

The only thing is that he didn't really seem like bothers with the OHC SBC anymore. He said he'd build one for someone who wanted it, but he's bored with them now. I'm not sure if that applies to the kits or not.

Hope that helps,

Jeremy

I'd be curious to know three things:

1. Are the implied horsepower gains strictly from being able to rev the engine higher, or are there any gains in the form of reduced frictional losses, etc.?

2. If 55mm LSx cams can be used.

3. If the adapters will accomodate shaft rockers.



That Donovan block with the 4-valve Infiniti heads looks downright menacing.

Hmmm, wonder if he would tackle a set of Dominion 32V heads...;)

I'd be curious to know three things:

1. Are the implied horsepower gains strictly from being able to rev the engine higher, or are there any gains in the form of reduced frictional losses, etc.?

2. If 55mm LSx cams can be used.

3. If the adapters will accomodate shaft rockers.



That Donovan block with the 4-valve Infiniti heads looks downright menacing.

It seemed to me that when it was tested on a dyno it gained something like 35 hp without revving any higher than a pushrod motor.

I'm sure you could fit any cam to this adapter, it just might take some work. The cams he uses are stock cams with every other lobe missing.

I have no idea about shaft rockers, call and ask him.

Jeremy

Edit: Bob, don't go ruining the guy's fun by making him try to get those heads to work on your motor. I think I might try that Nissan DOHC swap though, maybe we can line up if either of us ever finishes our motors.

There was a sprint car running out of Auto Speed Supply stables that had a set of hemi,OHC heads on a SBC back about '65/'66. They had a lot of trouble with it too. Don't remember the name of the heads though.

It seemed to me that when it was tested on a dyno it gained something like 35 hp without revving any higher than a pushrod motor.

I'm sure you could fit any cam to this adapter, it just might take some work. The cams he uses are stock cams with every other lobe missing.

I have no idea about shaft rockers, call and ask him.

Jeremy

Edit: Bob, don't go ruining the guy's fun by making him try to get those heads to work on your motor. I think I might try that Nissan DOHC swap though, maybe we can line up if either of us ever finishes our motors.


That Nissan head swap-- makes my head hurt.

That Nissan head swap-- makes my head hurt.

You need to see a picture of the intake ports though, I'll post one when I get home tonight.

The runner is a perfectly concentric cylinder, you don't have to port it, just bore it until you get to the bowl and then do some blending. I don't think they will support the kind of airflow needed for 2 per cube, but they should deliver some good low-end torque numbers as well as power up high (hopefully).

I'm still trying to get some answers out of the nissan guys about which heads to use. The VK45 is the predecessor to the VK56 (Titan motor). I would figure the VK56 would be closer to fitting but if they share similar dimensions I like the 45's intake better (more LT1 styled). I think the VH45 is the VVT motor, i'm probably not even going to attempt that.

Thanks for the input guys, keep it coming,
Jeremy

You need to see a picture of the intake ports though, I'll post one when I get home tonight.

The runner is a perfectly concentric cylinder, you don't have to port it, just bore it until you get to the bowl and then do some blending. I don't think they will support the kind of airflow needed for 2 per cube, but they should deliver some good low-end torque numbers as well as power up high (hopefully).

I'm still trying to get some answers out of the nissan guys about which heads to use. The VK45 is the predecessor to the VK56 (Titan motor). I would figure the VK56 would be closer to fitting but if they share similar dimensions I like the 45's intake better (more LT1 styled). I think the VH45 is the VVT motor, i'm probably not even going to attempt that.

Thanks for the input guys, keep it coming,
Jeremy


That makes my head hurt worse.
I would like to see the pictures. Maybe by them my headache will be gone.

http://forums.nicoclub.com/zerothread/179262

About 2/3 down the page the guy who started the thread "defrag010" posted the pictures.

Ya might get the flow ya need but ya are probably have to use velocity to do it and sometimes that ain't good.

I don't mind not getting 350+cfm flow numbers. To tell you the truth if I build a motor for those heads it will probably make use of light-weight internals not designed for 600+hp.

If you'll notice the size of the combustion chamber though, I'll bet building a high-compression motor would not be a problem at all.

We'll see though, I'm not really crazy about trying to run 8500rpm or higher with a belt driven valvetrain. I also have to find a machinist to modify a block for those head bolts.

Just wondering though, what's wrong with high velocity air coming into the heads? Is it harder to distribute evenly?

Jeremy

I don't mind not getting 350+cfm flow numbers. To tell you the truth if I build a motor for those heads it will probably make use of light-weight internals not designed for 600+hp.

If you'll notice the size of the combustion chamber though, I'll bet building a high-compression motor would not be a problem at all.

We'll see though, I'm not really crazy about trying to run 8500rpm or higher with a belt driven valvetrain. I also have to find a machinist to modify a block for those head bolts.

Just wondering though, what's wrong with high velocity air coming into the heads? Is it harder to distribute evenly?

Jeremy

Velocity is good to a point,but if it goes supersonic ya can't control it. Small ports and big inches and RPM's will do that.

Well I don't think a 302 will have that problem at 8500rpm, especially if you can bore those ports out to about 1.25". You'd know better than me though. How big do you think those intake runners are 90cc each?

Well I don't think a 302 will have that problem at 8500rpm, especially if you can bore those ports out to about 1.25". You'd know better than me though. How big do you think those intake runners are 90cc each?

Hard to tell in the pictures.

well they are 1.1" diameter. There isn't a very good shot to gauge length though.

damn,...I dont want to read this anymore..

my 302 is calling from the far back of the garage....give me dohc...I will love it..

I spun that thing to 8500 with the cam in block setup...hello 10,000rpm SBC

damn,...I dont want to read this anymore..

my 302 is calling from the far back of the garage....give me dohc...I will love it..

I spun that thing to 8500 with the cam in block setup...hello 10,000rpm SBC

Haha, at your own risk man. I just don't know about a belt driven cam moving at that speed.

I have to admit that I find this OHC conversion intriguing. If I understand dry sump oiling systems correctly, can't you set them up so that there is no oil pump inside the pan? What I'm thinking is that if you could eliminate the need for the crank to drive the oil pump, (in the conventional way), you could also potentially eliminate the camshaft and timing chain from the block as well. Even though you'd be robbing Peter to pay Paul in the sense that you'd still have to have an external oil pump driven from a belt on the front of the engine, it doesn't seem like the amount of parasitic drag that that pump would place on the crank would be as great as that of an in-pan pump and the energy required to turn a timing chain and cam. The crankcase vaccuum produced by the dry sump system would also allow you to use low tension rings and take that much more pressure off the rotating assembly: bonus. Of course, I realize that I could be talking completely out of my arse as I don't have any direct experience with dry sump oiling systems.


Does any of this seem even remotely plausible? (Barring expense?)

Well I guess it depends on which engine you are talking about. Obviously on the LT1 the cam drives more than just the Oil pump. But yeah, dry sump could have a more remote oil pump, and most people get an electric waterpump anyway. Getting a new distributor is a must for the high rpm you would turn with an OHC motor, so there is no reason to keep it in the stock position, cam driven. Of course you would also save power with a lighter valvetrain. I'm not sure if the cam/timing chain plays a big part in the belt/pulley system that drives the OHC's in Aardema's kit though. You might want to check on that first.

Jeremy

you could go to a coil pack system to deal with the high rpms instead of a disributor.

Don't you still need a distributor for the coilpacks? I can't say I know a whole lot about ignition systems.

i think it depends on the system but the one i was looking at(EDIS controlled by a megasquirt, i know i'm cheap) only needs a crank sensor, an EDIS module, and the appropriate number of coils packs.
more on EDIS here (http://www.megamanual.com/ms2/EDIS.htm)

I talked to Pete Aardema again today, I think i'm going to go ahead and try my hand at building a DOHC 302. The goal will be 450 hp and 400 lb/ft of Tq with an 8500rpm redline, anything more is just gravy.

There are still a few small details to work out (i.e. where to get a money tree).

When(if ever)i'm finished I'll start taking orders!!!:D

Jeremy

what are you going to do for cams...

how about a clone of the 30-30 dontov cam....or something with a little more lift

I talked to Pete Aardema again today, I think i'm going to go ahead and try my hand at building a DOHC 302. The goal will be 450 hp and 400 lb/ft of Tq with an 8500rpm redline, anything more is just gravy.

There are still a few small details to work out (i.e. where to get a money tree).

When(if ever)i'm finished I'll start taking orders!!!:D

Jeremy

A 302 LT1 or a SBC?

what are you going to do for cams...

how about a clone of the 30-30 dontov cam....or something with a little more lift

I'm going to leave everything stock for a while, until I know I can get it running as is. Just for the sake of simplicity.

As for LT1 or SBC, I think SBC will be the way to go. It's hard enough to convert SBC heads to reverse cooling, I don't think a machinist will touch nissan heads. That along with concerns about the waterpump and distributor, as well as Mr. Aardema being more knowledgeable with the SBC, he's my tech support.

I might try an LT1 if this works though.

Jeremy

Jerminator: did you happen to discuss the why's and wherefore's regarding cams with Mr. Aardema? It would seem that you could put any type of cam in there from hydraulic flat tappet to solid and they would all still "behave" like a solid lifter setup. Is setting valve lash still a requirement?

Also, did Mr. Aardema happen to mention if there were any limitations/warnings on how aggressive a cam you could run?

Jerminator: did you happen to discuss the why's and wherefore's regarding cams with Mr. Aardema? It would seem that you could put any type of cam in there from hydraulic flat tappet to solid and they would all still "behave" like a solid lifter setup. Is setting valve lash still a requirement?

Also, did Mr. Aardema happen to mention if there were any limitations/warnings on how aggressive a cam you could run?

I think you're right, they probably would all feel like a solid lifter setup.

We didn't talk much about the SOHC setup once he convinced me to try the Nissan heads. To tell you the truth he was very disinterested in his old work, got bored I guess. My kind of guy though, always looking for something new.

I could tell you the limitations of the DOHC nissan heads, but you might want to call Mr. Aardema about the conversion kit limits.

Jeremy

Just got my set of Infiniti heads in the mail!!!

I'll see if I can't post some pics tonight.

They look great though, it's going to be interesting to see how they fit onto the block. The main problem being the water passages.

post em up man...I got to see this

I agree, got to see this. ;)

hmm....subscribing...

my first thought was even if the bore centers are close...how 'bout the water passages?...interesting to say the least...

hmm....subscribing...

my first thought was even if the bore centers are close...how 'bout the water passages?...interesting to say the least...

Water passages into the head are not a big problem. The head bolt holes having to be drilled into them is.

Still don't have any pics, trying to find a camera. I'm still using 35mm full-manual SLR's:D

I'd worry more about the bolt holes than anything, maybe a LS1 block would be better for this since the head fasteners might work better in that arrangement. You can get a OEM dry sump setup then and run the ignition off of the crank reluctor wheel so you don't need the cam at all.

The cooling setup is what worries me.

Either way it's too bad you are in NC cause id like to see this just for curiosity sake.

Bret

so its gonna look like this:
http://www.aardemasohc.net/index_files/Page2197.htm?

those are some MASSIVE heads. what are you going to put this engine in?

so its gonna look like this:
http://www.aardemasohc.net/index_files/Page2197.htm?

those are some MASSIVE heads. what are you going to put this engine in?

Correct, Mr. Aardema said he would send me some pictures of his setup to give me a better idea on how he made it work.

Not really sure what the motor will go in, something small for sure. I might try to build an aluminum tube monocoque around it. It'll be a while before I have to worry about that.


Bret,

Where are you at? I may need to talk to you when I change the cams out. I can't seem to find anyone who makes blanks for this motor so I'll probably have to do re-grinds:(

Jeremy

How do these things do on lubrication in the 7500 rpm range?

How do these things do on lubrication in the 7500 rpm range?

You got me, Bret had a good idea with using a dry sump LSx block. I guess to be safe if I do use a conventional wet sump I can get a 7 quart pan and a high volume pump. But Dry sump is probably the way to go.

Anyway, thats a good point, I'll keep it in mind.

Jeremy

Bret,

Where are you at? I may need to talk to you when I change the cams out. I can't seem to find anyone who makes blanks for this motor so I'll probably have to do re-grinds:(

Jeremy

Jeremy,

I'm in NY. I know someone can do regrinds for them though.

Bret

Jeremy,

I'm in NY. I know someone can do regrinds for them though.

Bret

I know I can get regrinds. The question is to what specs will they be ground?

These are uncharted waters I'm sailing in now...:shock:

I'm up in Baltimore on occaision, maybe I'll have to ride on up to NY and check out the famous (infamous) Bauer Racing.

I'm going to DC next weekend to visit a buddy.

Bret

I'm going to DC next weekend to visit a buddy.

Bret

Even though I may be up there next weekend I'm afraid the best I could show you is a stock set of Infiniti Q45 heads:shrug:

However, I do know a guy in 20744 with a set of Q45 heads. He says they are low mileage 89-93 style. I think he only wants $400 or so for the heads and intake. Not sure if you'd be interested in the challenge.

I'll let you know if I make it up to Maryland this weekend.

Jeremy

And I thought my Dominion 32V heads were cooler than Fonzie! :D

And I thought my Dominion 32V heads were cooler than Fonzie! :D


Rest assure they are! They are my friend! I've always wanted some, and in '98 a friend of mine put a deposit down on some, then went broke, so I never got to see them and how they performed.

DOHC engines are sweet!

Wow this is an old thread!

It's a shame I got busy building another project and I still haven't worked on this one. In fact the heads are up for sale.:cry:

Oh well, maybe one day....

bah I just read this whole thing to read the project was abandoned!!

well, it doesnt look easy I will say that. I would attempt it if I had a bottomless pocket.

bah I just read this whole thing to read the project was abandoned!!

well, it doesnt look easy I will say that. I would attempt it if I had a bottomless pocket.

Yeah it sucks. But if those heads don't sell before I move then I'll keep them and work on it when I have a garage again. I don't anticipate it costing a terrible amount of money (that's a relative statement of course) but I will have to buy a new welder ($2-5k) and the block I want to use runs over $3k.:(

Does anyone know the difference in the bore spacing between an LSX block and an SBC?

Thanks,
Jeremy

I could get someone to do my welding, the main problem would be getting the perfect valvespring components (problems I see). Anyone have a diagram of a nice OHC valvetrain layout?

I could get someone to do my welding, the main problem would be getting the perfect valvespring components (problems I see). Anyone have a diagram of a nice OHC valvetrain layout?

That's actually the easy part (as easy as you could hope for anyway). There is a guy on one of the Nissan forums who did some measuring and testing and milling on a set of these heads to see what he could do. He found that there are some SBC springs that can be made to fit these heads and thereby allow you to run more aggressive cams.

The hardest part should be setting up the timing belts or chains, especially if you go for chains. Pete Aardema has had success with the belts though, so that is probably how I will do it.

Edit: I did a little research and it seems that the bore spacing is the same for the Gen III engines as it was for SBC's. I might just have to pick up an iron truck block and get back into this project.

I know this is a old zombie thread back from the dead. I haven't been here in awhile(2005) and logged in to read this thread hoping to see some developments. Cool ideas though.
Nice to see some one is thinking outside the box.
I really like DOHC V8s and hope GM will improve on the northstar or build something I can try and get and play with.

I know this is a old zombie thread back from the dead. I haven't been here in awhile(2005) and logged in to read this thread hoping to see some developments. Cool ideas though.
Nice to see some one is thinking outside the box.
I really like DOHC V8s and hope GM will improve on the northstar or build something I can try and get and play with.

Eh, I haven't really pursued this one due to some other projects. I still have the heads and a few other odds and ends in my house right now though. Maybe one day I'll find the time to start on it again.

Lately I have been looking at motorcycle heads to see if I can find something that will fit. There is hope in a drag racing version of the ZX14 heads that has bore centers very similar to the Ford 4.6 modular motor. I'm still looking into that one though.

For what kind of project?

For what kind of project?

Think C5 corvette with the motor behind the driver.;)

That's my latest and greatest idea anyway, I'm going to talk to a guy one Friday about building the chassis. I would like to do that part myself but it's hard to argue with a tried and true mid-engine chassis setup for under $10k, and I just don't know enough about chassis building to guarantee the same result.

From there I'll buy a high mileage C5 and start chopping up the body panels and fabricating my own to fill in the holes, basically shortening up the front and extending the back. I'm still not sure what to do about a transaxle, the riccardo unit in the Ford GT has potential to handle the power and still offer 6 gears, otherwise maybe a Mendeola setup.

I've been talking about building a big cube gen III based on the new GM LSX block but obviously this is a novelty project so a novelty motor (i.e. 4 cam) might fit in well. If I can't get it to make power I can always add a few turbos.;)

Don't expect this project to progress any faster than the Infiniti headed SBC though, it's a lot of money to throw around.