V8droptop

So, per Bossfrog's website, their subframe doesn't require firewall modification, can run a stock ls1 oil pan, and basically plops the motor into the engine bay without a lot of cutting, correct?
Kit #1 – Engine Subframe (LSx) – this kit includes a professionally designed engine subframe, precision built in a welding fixture for the best possible fit. Our plasma profiled mounting brackets and heavy wall rectangular tubing are much stronger than round tubing subframes, and we reinforce the front crossmember and uprights to gain additional strength where it is needed. Our kit does not require cutting into the transmission tunnel, dashboard removal, oilpan modifications, or additional steering joints. The only changes from stock are some trimming of the engine bay gussets, swapping the lower steering knuckle for a slightly longer version, and relocating the sway bar slightly forward.


This, versus V8R's kit which requires cutting of the firewall, custom oil pan, and a few other items to be moved/chopped etc.

From the pictures on the respective sites, it is obvious the V8R kit sits lower and further back, by a noticeable, 1-2inches in either regard, correct? Is this the main reason for all the extra effort in the V8R kit? Do most people feel that is worth it?

I've been aiming for the V8r kit, but the ability to use a stock oil pan, and a few other things are leaning me to the Boss frog subframe. However, I'd want to use the V8R headers, which probably wouldn't fit easily.

THoughts on this?

ttype

A couple years ago I found a site by a guy that listed alot of the differences between the companys mounts.

Unfortunately I don't have the site favorited.

Maybe someone else remembers the location ?

cxmoney

this is all I can find ttype, maybe this is what you were talking about? - Swaptastic - Nathan Sumner

charchri4

Yes the swaptastic site ^^ is the best I know of for head to head comparison. I think everyone goes through this question and works it over so welcome to the club!

To me the question is really more about you than the car. Are you the kind of guy that goes all out never doing anything half way? Do you enjoy fabricating and have no fear of pulling the trigger on a sawzall and welder? Are you OK with putting in a couple dozen more hours of work to have a better car in the end? If yes to all then V8R for sure. If no to any than you should consider the BF frame but do not use their diff mount. Routing exhaust is a PITA around it.

Another little point most folks miss is the shifter comes up in the perfect spot with a V8R frame. I don't know what provision BF makes for that but if the engine sits 2 inches farther forward either the shifter or tunnel would have to be modified to work.

To answer your question yes I felt the V8R kit was well worth the extra effort but then I also seam welded my car and added 5000 lbs in bracing most guys don't do so I'm the wrong nut to ask that.

I wrote a post just for guys doing the research you are doing now that you should checkout. http://jimsmiata.blogspot.com/2014/0...-v8-miata.html

Welcome to V8miata.net! I'm looking forward to seeing your car and what you decide to do.

V8droptop

To elaborate on that, the only real reason for looking at the BF front subframe is because I'm using an LS7 with OE rods. About any factory pan can clear the rods, including LS1, which fits unmodified in the BF setup.
With the V8R setup, the only option is their steel pan (even more money, hooray), which still doesn't fit, but would have to be modified to clear the rods.

The motor was a dumb choice in a lot of ways, but I bought the LS7 bottom end, had it rebuilt with wet sleeves (originally it was going to be ERL Superdeck, but its a waste without N2O or Boost) and am doing ported heads/cam/ported fast102, and trying for a halltech Superbee intake.

So, its a well sorted motor. The problem is wrapping a miata round it. I want to go V8R, but the oil pan, and then the strength of the subframe are my biggest questions. The BF piece looks more sturdy, albeit less fit-and-finished.

My diff is already V8R and in. I liked their stuff, but it was a bear to get in.

Thanks for the reading, guys, Its on my reading list tonight, but I'm at work still.


***Sorry, but while I'm here, what is everyones prefered choice of front drive? I was looking at LS1 setups as easiest, but It seems CTS-v/GTO ls2 would leave more room, correct? I'm debating front accessory drives currently as well, as I'm going with a damper.

Meierznutz

Nick, the BF kit allows the F-body type pan without mod. I had to dimple the firewall near the bell housing just to be sure the bolts wouldn't hit....didn't want rattles in the car.
I didn't follow the script for accessory drives as I wanted to use the stock Miata pump and lines. I used a late NA pump with the outlet turned around (late pumps use one retaining bolt so it can be clocked) and brackets I made from 1/2" 6061 to mount the pump at the oil pan seam. It ran off a 4 rib belt on the rear of the Vette Harmonic dampener. The water pump and alt ran off the 6 rib. I also made a bracket for the alt that put it high to the driver's side head. The idler and tensioner were repositioned and gave greater wrap to the pulleys. I still have the templates if you want a set.
Of course I also moved my radiator forward to clear the fans. I used stock Miata for them and had Griffin make me a 3 1/2" thick rad core. It was easier than you would think. Now that prices have dropped on used brackets you might want to try a stock set up but mine worked flawlessly.
Personally, I can't say enough about BF's customer service.....

charchri4

LS7! LOL well yeah you are a go big or go home guy for sure. Flying Miata tried a number of ways to make that work and abandoned the project. Easier to just build an LS3 for the guys that want more than 500hp...

Beyond that I can offer nothing other than I wish you the best of luck and you NEED to do a build thread before you do anything else! I really want to see this monster!

V8droptop

I did read about the FM attempt, I think it was a matter of kosher ways to make it fit.

V8R says you can take the Steel oil pan and clearance it with a ball peen hammer to clear the bolts.

Or, alternatively, the BF kit shouldn't have a problem. I wonder as you mentioned about the shifter, though.

Noted on the drive setup. I was thinking of going Corvette setup, I think. Simplicity sake, really. And either a turn-one pump, or jsut their restrictor to keep the feel correct. I haven't decided on the radiator yet, as I kind of want the engine in.

Another big hang up for me, is the intake. I'd prefer to do the OEM style Halltech vette intake, which goes over the miata core support, but this removes your latch system. I don't think I can live with hoodpins, so I have to get very creative there, or else run plumbing like most do. However, the Halltech Superbee intake is about the best piece out there, and would be nice to get it to fit as it was meant to on the car.

I suppose I could do a build thread, but I always feel its lackluster or boring. Its a car with nothing in it right now :-D

Meierznutz

Aero-catch makes some flush mount latches that are just the bomb.
I learned the hard way that if you use regular old school hood pins that you need springs under the hood or the pins can work loose. My Simpson Design hood took outy windshield. NOT fun with my son in the car.
By the way, The BF sub frame kit uses Hooker Block Hugger Headers with a dimple angled across the collector on the DS to clear the steering shaft. Then if you send your universal knuckle to them they will modify and return yours as it needs a small extension added to it. My shifter popped up right in the center of the hole in the floor, stock boot fit over it. I used a B&M but cut 3" off it for proper feel.
Yes the BF rear diff mount leaves little room for exhaust but it can be done. For my car I went under the diff by going with larger pipe and flattening it to an oval. The cross section kept the overall flow rate to the same flow area.... then it was "adjusted" for real world clearance (by a few of CT's famous road deviations) and worked out just fine. The good news is that with just two joints to unbolt and a couple rubber hangers the entire exhaust can be dropped in one piece.

V8droptop

Those are about as slick as it gets. Very nice. Maybe that is just the ticket. Looks a lot like things we use at work. Just need a key in them to keep from the goodies going by-bye

Aerodynamic panel fasteners from Aerocatch

Meierznutz

Aerocatch makes tem with locks.
http://www.aerocatch.com/aerocatch/p...eries/120-3100

V8droptop

Its items like that which keep the fit and finish nice. I think I'd love to go that route. If it gets me the 15whp the intake is good for, I'd drool. I think I do prefer the top mount vice the bottom mount piece as well.

Flyin' Miata 1 800 FLY MX5s : Cars for sale
There you can see the intake setup and aerocatch pieces.

charchri4

I love mine. A lot of guys use 4 of them with no factory latch.

I wish I had left them on the car when I painted it and yeah I still have some gaps to adjust...

LS John

Another old post, but I got the first LS subframe that Martin sold to the public, so that is what we tinkered with and made a few changes. We notched the firewall back about an inch, and about 2 inches around the bellhousing, to make everything fit. His steering rack brackets didn't fit, so those were changed, but everything else in his kit was spot on. With the 6-speed, the shifter is right in the center of the hole.
The fabricator that helped me said it was so much faster than doing it all from scratch.