SinisterRoadster91

I have my engine sitting in my engine bay as I tried to mount it using the stock subframe. It's clear I will have to make a custom subframe to get the engine sitting the way I want it. I can weld and am not afraid to tackle such a project. My question is, after looking at swaptastics pics, where exactly are the subframes different from stock to custom? My main concern is throwing off the geometry of the suspension if I don't elongate the frame in the proper areas. Anyone have dimensions or can shine some light on the subject?

Gator Bait

I usually hate on people that do this to others....but you appear to have not read a single line of build posts. You're going to have to search and do some reading. Depending on your motor choice, some search terms "Monster Miata" for Ford motors and "V8 Roadsters" or "Flyn Miata" for an LS motor. V8 Roadster also offers a front sub frame with no engine mounts so you can do whatever motor in the position you choose.

MX-Brad

I have a modified subframe for a 5.0 conversion so I can answer some questions for you, but it's not clear if you're doing an LSx or 5.0 swap.....

SinisterRoadster91

I'm not doing a v8 of any type which is why I'm trying to get a good idea of what others have done too adapt to my situation

cvx_20

The main reason for modifying the stock subframe is to gain header and oilpan clearance. There is a practical limit on the width, I think around 21" or so. I did this years ago for a 302 into a 1991, here is a little writeup I did.

MiataV8 Conversion: Modified stock subframe

That subframe is still in the car, I try to drive it every day.


There's really not much specific to the motor except the mounts, the steering rack is the main interference point for the pan, the steering shaft is the main interference point for the headers, same problem with LS or 302. The 302 is a smaller motor, has fewer clearance issues. Don't be shy about offsetting the motor to the passenger side to gain a little clearance, Corvettes and Vipers come that way from the factory.

Sorry, missed the post that said you weren't using a V8. What are you using?

Mike

MX-Brad

Not sure what you're asking, so this probably won't help.....but if I set my modified subframe next to a stock subframe, the main differences are the modified version is channelled on the pass. side to allow room for the starter, and there are a pair of square stock pedestals welded up front to accept engine mounts. there could be other differences too, but that's what jumps out at me. No changes were made to suspension mounts.
But this is for a Ford swap.....100% not applicable to anything else I'm sure. Good luck.

SinisterRoadster91

Thanks for the link. The issue I'm having is oil pan clearance. The oil pan simply hangs too low below the steering rack/crossmember. I can't raise the engine without having to have a obnoxiously huge hood scoop. So what I want to know is can I elongate where the subframe meets the chassis essentially a body lift, will that throw off anything? What else would need to be changed? I need a little over a 1" more clearance

I'm using a VQ30DET, essentially a turbo 350z engine.

Gator Bait

The LS guys have to get "special" oil pans. The Ford guys go with clearanced hoods with scoops. You have to figure out what can be done. Interesting swap though. I like seeing new paths cleared.

SinisterRoadster91

Is that not what's going on here from swaptastics website?

SinisterRoadster91

The subframe in the pic above is clearly longer where it meets the chassis of the miata. Can anybody tell me if that was all that was done or was some other things altered such as control arm mounting point etc.

Gator Bait

The conversion sub frames use all the stock Miata mounting points and geometry.

cvx_20

It looks to me like the fabricated subframe is resting on something that raises it up. The key points, suspension mounting tabs, steering mounts and upper mounting points that attach to the car, all seem to be higher than the stock subframe, as if the whole subframe were elevated.

It also appears to me that there may be something wrapped around the upper mounting, maybe shipping stuff?

At any rate, what you're suggesting has been done before, the Ford 302 is quite a tall motor and it's sort of a juggling act to get it to fit without going thru the hood. It does affect the suspension travel, as the net effect after adjusting things to get a decent ride height is the same as when the car is lowered.

Some have notched the pan to gain extra clearance, the steering rack/pan interface is the problem with the 302, but the pan can be modified to lower the motor quite a bit. I didn't need to use the spacers on mine, just cut the webbing out of the hood where necessary.

Mike

SinisterRoadster91

Thanks Mike this is the useful information I was looking for.

Meierznutz

OK, so plowing through all the bullshit and blabbing, you are doing the Nissan turbo V6 into a Miata. NA, NB? Power steering, manual, or de-powered Power rack? Have you measured the height/width of the long block?
From experience, the LS has 2 mounting positions, forward and back. The forward position (some V8R, Boss Frog) allow stock f-body oil pan and no trans tunnel mods with the LS. Rear needs no rack mods but means oil pan mods and trans tunnel to be sliced to fit the t-56. Ford 5.0 may need the subframe spaced downward to clear stock hood.
For your swap you will be in some rarely charted waters.... I have heard people talk about this swap but haven't seen one completed yet. Since you are "Off book" with this one you will be the source that others will come to. I suggest that you make patterns of the parts you create and track mods to the parts with the patterns. If you stick with the stock subframe you will have something that others can start from. I would suggest that the V8R tubular might give better clearances and provide the stock body pick up points eliminating having to fab all of that first. They even come with rack mounts s you wont have to worry about being off center or bump steer issues later. Oil pan and cooling mods are all up to you as well as getting the ECU to talk to the car.
Best of luck and keep us posted o how you are doing.

charchri4

Hey Sinister sorry to have missed this back in Sept. The first posts didn't go so well because you were so vague it really did look like you were just a troll.

I think you would find some useful help here on your situation just because guys know these cars so well. BUT you need to be forth coming with details on what you are doing and what trouble you are having right from the start. We won't kick you under the bus for doing a V6 swap but when it takes a page of posts to figure that out it's really difficult to work with you. Had you posted photos and details of what you are doing and what you need you would have had good info on the first page. Also you should fill in your location because there might be someone close that has a car or parts laying around that would jump in with a solution.

I'm going to cull some of the needless posts from this thread and give everyone here a do over.

Meierznutz

Eyeball measuring it look as if the custom subframe is taller, but if you measure from the upper control arm to the lower, the frames are equal height. The thing that throws off your eye is the steering rack mount. It is mounted lower on the front tube to give pan or crank pulley clearance. That is what id causing the whole sub to sit higher and look taller.
The Ford swaps routinely add a spacer between the subframe and the body (a body lift) of up to an inch to get the carb'd 5.0L to fit without a scoop. I can also say from using one that the Simpson Designs hood allows more room over the engine and at the nose without looking out of place.