got my tubular subframe
 

Ordered a mountless tubular front subrame. Fit is spot on. No pushing, prying, etc. to line up any bolts.

Two points of criticisms however.....

1. The advertised weight savings with mounts is 10lbs. Mine with no mounts is 8lbs lighter than stock.

2. When they build it with mounts, they cut the ends of the front tube where it curves back and joins the rails that run parallel to the car. On the mountless, those ends extend back until their natural intersection which means they are in the way for attaching my own mounts. Not a huge deal but I just wasn't expecting it.

Making a jig off the stock subframe to fab solid aluminum motor mounts and their attachment to the new subframe and then onto building tubular adjustable upper control arms and tubular lower arms.

It's Febuary 18 already?!?!

Pics pics pics

Where did you buy it from?
Any pics of what you are having to do to make your mounts work?
I am considering making my own sub-frame for my LS1 swap so any pics will be appreciated.

Bought it from v8roadster. Pictures on their site. Haven't started fabbing the mounts yet. Hoping to work on the jig tonight. I'll post some pics once I make some progress.

Gotcha, wasn't sure if there was maybe another supplier out there that I didn't know about. Thanks anyways, and I'll look forward to your finished work.

Jig made on the stock subframe and then bolted to the new subframe. Started on the mounts, but no pics yet.

Looks like your putting stock mount locations on it. Why not just get their mounts installed? or do you have some super secret reason.

Personally I plan to move the engine back a few inches for my next build.

The mounts they provide only match the mounting surface of the factory subframe and are meant to still utilize a factory style multi-piece rubber mount to the block. I don't want that! We are going with solid mounts and rather than fab a solid mount that goes between the optional mounting point and the block, it's easier to fab the whole thing from the subframe hoop up to the block. Not sure if that make sense as described, but when I post pictures it should make sense.

I know his would be an off the wall question, but what is the measurement from behind the front loop at the steering rack to the fire wall. The reason for me asking is I'm doing a engine swap and I want to know how much room I have for the oil pan.

Well I won't be able to finish the other motor mount until next weekend and so I won't be able to remove the jig and bolt it up to the car until then. Shoot me a pm next week and remind me to measure for you.

I hope your using locktite on every single bolt on the car if your using solid mounts. I think the AWR mounts are as stiff as is ever needed.
These engines have serious vibration.

Bob

But if you fab the mount a bit from the subframe the total may be lighter than using the AWR ones.

Using the AWR with the race PU feels like being at the dentist. :2cents:

Keep up the good work!

+1.

Plus, I don't think there is a lot of performance to be gained there.

Saving 2.2lbs per mount from stock. This is no dual purpose application fellas. I could see your point if I was turning some miles in the car or spending some time behind the wheel. 60 seconds at a time. That's all I'm after.

Looking to loose another 30-40lbs off the front. New subframe and mounts=12.4lbs toward that goal.

Seems like in XP where you can run a completely different type and make of engine you should be able to shift it back. But now I’m confused section 17 Prepared rules 17M7 says the engine may not be relocated. If you replace a rotary or a 4 banger with a V8 what exact placement is it that does not constitute relocated? And the Prepared rules say that Vehicles prepared to Production GT classes are elegible. The XP rules say the engine orientation must not be changed (i.e., transverse stays transverse, longitudinal stays longitudinal). And it says vehicles prepared to production GT classes are not eligible. The GCR production GT rules allow the engine to be shifted back just so long as the front spark plug hole is within an inch of the centerline of the front tires.


Ouch my head hurts.


I wanted to move the engine back and keep something that would fit in the production GT rules

Seems like combinig XP solo and club GT rules it is saying put in a rotary engine to have the best setup within the rules.

But you cant combine the rules. You either have to comply completely with the GT rules (minus any exceptions the solo book specifies) or you must completely comply with the solo rules.

I can help some one the XP rules front. You can move the engine as far back as the firewall will allow. The firewall is "sacred" in Prepared. You can notch it and "clearance" the firewall for certain things and not for other. And you can't just modify the firewall for 1 part and move the illegal part into the newly clearanced area.

The simplest rule for engine placement in XP is the head(s) can not go past the factory location of the front firewall.

You must go to a Mod class (D/E) if you want to move the motor back farther than that.

Correct. The firewall is the key. The firewall cannot be moved back or clearanced for the engine. In XP the only other engine placement rule is the orientation. With a big(for a 1.8) twin screw charger, hanging off the side and the big TB we're running, there is no room to move things back.

Removing the cam angle sensor and it’s got about 3 inches it can go back plus the rules allow for notching the firewall for a "distributor" if I remember correctly. Head or block are the only parts that count. 3 inches is also within the Club GT rules. I want to be able to road race the thing I intend to build.

The part that sticks up that does not separate the driver from the engine compartment is not part of the firewall and can be removed. moving the engine back 3 inches will allow the radiator to be moved back and slanted in behind where my sway bar will end up witch will further help in moving necessary weight back and down.

Those pictures make me want to tear my still not back together car apart to cut more stuff off.

Can't run a GT spec car in XP period but I don’t see how that stops you from building a single car that can comply with both sets of rules at the same time.

Seems like the best way to do this however is might be to build a Simi tube chassis Miata for GT2 with a rotary. The 15X7 max wheel size for GT3 is killer but I suppose you could run different wheels for the different applications.

So, given the desire to move the engine back: What is the easiest way to handle the PPF? The diff mount is relatively easy to work something different up. The transmission is a little harder. I'm not keen on doing the cross frame rail transmission bracing that the V8 conversion do.

This is on the list of stuff to do to the XP car... eventually.

Are you allowed to modify the PPF in your class. Its kind of sketchy in my class, I define the PPF as a drivetrain mount so I can mod/remove/replace it but it might not be one to some people. If you can mod it, hack it off in the middle somewhere and weld it back together. You should then get it solution heat treated to get the strength back but that may or maynot actually be required.

Cut a little off each end and re-drill holes was my plan for PPF. That and make a shorter drive shaft.

XP allows swapping to completely different engines like a V8 or a rotary which requires changing drivetrain mounting entirely and figuring out how to position it so I can't see why shifting the stock block motor back as close to the firewall as you can get without having to modify it for any part of firewall for clearance to the block or head would be an issue.

I say that but every time I try and interpret SCCA rules I get confused or pissed off.

In Prepared, the transmission is "open". If you swap out to say a T5 or T10 style unit. None of those have tail housings to connect to a PPF or torque tube. You would have to create a mount somehow. Abusing the PPF and chassis would be legal from what I read of the sections, 17.2.B/C/D.

XP is a slightly different beast.

I doubt you'll meet many DP (or FP) Miata that have abused the PPF to move the engine back. It is a lot of work. The Nationals winning DP (I know the owner) for the last 2 years is well enough weight balanced for pushing the engine back to not be necessary. Sure a 10/10ths build would require it. But with Solo, I think more seat time and tire testing will benefit over the slightly better weight balance.

I'll have to spend some time with the spare PPF I have. I dont know if you can get away with just redrilling the mount holes. IIRC, the PPF gets taller at the transmission and diff. I think the easiest way would be chopping a section out of the center and reinforcing to make it more like a tube than C-channel frame.

Well if it's still not back together what is holding you back? Cutting stuff off is free and fun. Of course what you have to do BECAUSE you cut stuff off isn't always cheap or easy - but it's usually still fun!

12.8 pounds net savings.

A light grey paint is useful for finding future cracks. :)

Looks good but getting the engine in would be a nightmare for me.

I think the procedure for installing an engine would be
1) install engine in sub frame
2) lower car on lift down on sub frame

I haven't read or heard anything about these subframes cracking. Do you know something I don't?

I was just extrapolating the vibration from the engine transmitted through your new mount "towers".
It's not alu of course, but it never hurts to catch cracks early (e.g. check each time the engine is out).

But if it doesn't crack or break slightly, it's to heavy :)

I am looking forward to knowing if that is the case. I think it may have been better to have a wedge shaped spacer between his mount and the block. Or even just a flat spacer that is slid into place after the motor was lowered between the mounts.

Looks good. I agree it would be fun to get the engine in there but probably doable with some helping hands. I usually end up pulling/replacing my motor solo though.

As far as cutting more stuff off: The car HAS to be ready for the Texas Tour in a few weeks. Just fired up the new motor for the first time last night. :D

There are aluminum spacers that go between the subframe and the block. They are bolted to the subframe in the second set of pictures.

I'm not too worried about getting the engine in. However, pulling the engine and tranny together won't be an option any longer without dropping the new subframe.

Not bad at all. That is once the engine hoist was lowered back down and the tranny removed from the engine.:rolleyes::rolleyes: didn't think that one through. Tranny had to go up from the bottom.