Question regarding LS1 swap
 

I was just reading on Granny's website that they don't suggest the LS1 swap and that it requires the hood to be modified/or the steering.

Now I was under the impression from many that I have talked to that the LS1 swap wasn't too incredibly difficult. Those who have or know someone who has performed the swap.... is this true about the hood/steering?

Or is their site not updated?

Hinsons setup is slightly different, checl w/ them.

Read this thread...

https://www.rx7club.com/v-8-powered-rx-7s-299/i-just-bought-ls1-engine-494858/

That doesn't look promising. :wallbash:

The Hinson setup uses an adjustable tie rod end to correct the steering gemoetry. No big deal. Hot rodders have been using them for years.

Many of us have tracked the car at high speed with the HSC setup with no bump steer issues. The myth of bump steer is almost as perptuated as the myth of ruined weight distribution and killed handling. :rolleyes:

From what I've gathered though, the Hinson set up is about 9K? Ouch..

Hinson's mounting setup is about $1500. It's the rest of the build that will get you up near or over $9K. Yuo're not going to save all that much by using Granny's stuff. IMHO If you're not willing to drop that kind of money into the car then you shouldn't be looking at a swap.

I was reading one of Jim's threads, and it appeared to me someone was saying that all of the mounting parts were 9k and that was without and engine and tranny which is another ~4k. So we are up to 12k-13k for the actual swap.

Or since Jim is due north of me just a little bit... I could bring him some beer and sammiches and burgers in exchange for his non-mass produced help? :rlaugh: :icon_tup:

www.hinsonsupercars.com Read and check out the prices for yourself...e-mail them directly with questions...they can send you a full spreadsheet of costs etc...if you wish i can send you one as well.

Likely because it's as little understood. :D

Not sure where you got that idea, but you should never consider the listed cost for parts on my car as indicative of "standard" conversion costs. I buy all new parts, including lots of upgraded aftermarket pieces and hardware, and I've footed the bill for all the R&D costs of the Cobra IRS conversion setup and my engine cradle. I probably do have around $9k in just my "conversion parts", not including the engine(s) or transmissions(s), but that isn't representative of normal conversion costs.

No no, not you specifically stated that price.

Someone said that, that posted within your thread.

So how about some beer and burgers? :icon_tup:

For helping you with your car? Sorry, I rarely feel like working on my own car, and unless you can change the Windows and Office product schedules, I don't have time anyway. :)

Heh, I was more talking about... cohersing you into fashioning some of the kit necessary for an LS1.

You have the well documented experience in this whole mess, and their kits (Grannys and Hinson) are fairly expensive in the grand scheme of the whole thing. I mean we are talking about spending equal or more than the cost of the engine and tranny on supporting the engine. :P At any rate if I could talk someone with your experience into fashioning a kit for me like yours at a price less than theirs.... I'll buy all the beer I need to :D

Considering the way everything is done up on Jim's car, and that the engine cradle I'm buying from Jim is about twice what my Hinson cradle cost I'd guess you're delusional at best if you think that Jim is going to fabricate you an LS1 kit and have it be cheaper than either HSC or Granny's. The Hinson kit works just fine for an LS1/2/6 motor.

Seriously, if you're worried about costs escalating then you might want to find another project. Pay to play.

Already working on it.

https://www.rx7club.com/attachment.p...d=147275&stc=1

Who charges $2,000+ for an engine cradle? Well, besides Pettit Racing... :D

Sorry to disappoint, but my parts cost whatever they cost. I won't cut corners to make them cheaper than someone else's and I don't gouge people to make them more expensive. I don't have to sell any because I don't do this for a living, which is good, because I rarely make any money from it. :)

Hey Jim I'm sure you've been asked this a billion times already, and I've just started looking at these forums, so I hope a few more questions wont hurt ya =).

Recently i've been helping out a bud whos been doing an LS1 conversion using hinson parts. So i've seen hands on what it takes to get their subframe to line up, and the quality of their parts. I have no complaints thus far, but I do not personally know too much about other kits in comparison to hinsons; nor do I know anything of their customer relations.

My question for you is, what advantages will your frame have over the hinson counterpart? If one were to purchase your frame, would there be any complications in using say the hinson parts in combination (driveshaft/torque arm), or certain aftermarket parts ( intake etc) that would be better used with your subframe?

Initially when you start making them will you be offering a group buy with limited availability or will you be making them in relation to how many orders you get? And lastly: Do you have any estimated date for when you will start, and an even loose price range?

Thanks =D

Professional TIG welding and the choice of mild steel or Chromemoly tubing aside, my engine cradle doesn't require a core like Hinson's because it's a complete replacement and doesn't use any part of a stock cradle. Neither does Grant's (Granny's), but mine is far stronger and more rigid than his, which is made of stamped sheet metal and thin wall tubing, plus he's had fitment issues in the past which may or may not have been resolved.

My cradle also has machined steering rack mounts instead of box tubing with a notch and a couple holes in it like Hinson's and Grant's. They precisely fit the steering rack bushings and prevent excess movement of the steering rack.

I'm also the only one providing an option that goes beyond a torque arm, and in fact, I eliminate the need for a PPF/torque arm altogether. The Cobra IRS conversion provides wide choice of gear ratios and greatly improves the strength of the differential and axles while giving you more room for the exhaust system.

Granny's conversion kit...
https://www.rx7club.com/attachment.p...d=147855&stc=1

Hinson's conversion kit...
https://www.rx7club.com/attachment.p...d=147856&stc=1

My LT1/SBC cradle...
https://www.rx7club.com/attachment.p...d=147857&stc=1

My Cobra IRS conversion kit...
https://www.rx7club.com/attachment.p...d=147858&stc=1

My LSx engine cradle will have dual mounting points and will use the superior Corvette motor mounts instead of the F-body "clamshell" motor mounts.

The front mounting point will position the engine for clearance of stock intakes and will work with Hinson's other conversions parts, should you choose to go that route, although I'll eventually be producing a transmission mount with the option of an integral front driveshaft loop and a mid-rear trans tunnel brace with the option of an integral rear driveshaft loop to meet NHRA regulations.

The rear mounting point on my cradle will position the engine farther back in the chassis (about 2", as show in the picture of the LS1 mock-up block) and require a custom sheet metal intake that I may or may not be able to "mass" produce. The benefit is improved weight distribution, more room in front of the engine for accessories, and a significant horsepower advantage from the sheet metal intake. You'll also be able to use an LS7 dry sump oil pan (or an LS7 crate engine) with my cradle.

Group buy only. This is just a hobby for me and I don't intend to carry any inventory. However, my turnaround time will be far shorter than Hinson's though. For example, my fabricator is just finishing 25 of the Cobra IRS cradles shown above and it's only been about 3 weeks. :)

As soon as the Cobra cradles are done, we'll be finishing up the first two prototypes of my LSx engine cradle, so it'll likely be before the end of the month. I estimate about $900 for mild steel and $1,100 for Chromemoly, which is about 3-4 lbs. lighter.

Thanks for the detailed reply! I'm not sure how anyone wouldn't be sold after comparing what you're offering at a very fair price :)

I agree, I want one!

Jim,

Speaking strictly LS1 w/ stock intake/ T56 combo and your cradle...

I know your car has the P/S removed/bypassed. Will your cradle allow me to retain P/S if I so choose?

Will the bump steer correction be available with your cradle?

Also, I most certainly hope you plan to produce a T56 transmission mount. These pictures I have seen of the Hinson mount basically ripping the floor board out of the car make my very apprehensive to use it, to say the least.

Thanks again,

Mike
(Labreck Bushing Group buy, and Cobra IRS Group Buy Vet!)

Drew still wants all that stuff, so it'll be taken into consideration. :)

Hinson's "bump steer kit" is actually provided by a third party and is readily available. Spacing the tie rod ends to correct bump steer is nothing new.

I sort of have to produce one... I have a T56 also. :)

Without the torque arm attached to it, I don't know if it's a problem or not, but those mounting points were never meant to handle a lot of load. I'm considering a single brace to tie all 6 mounting points together, sort of like the Mazdaspeed or Auto EXE brace systems. I really don't want to have to drill holes in my floor pan, but if that's the best solution, I'll go that route.

No PS here. I have the rack looped. If it doesn't bother me I may get it permanently converted by Maval.

I am/was hoping to add AC, but that's only because it gets damn hot down here. :p:

Well, we might as we turn this into your product thread. :) Does the above statement indicate the possibility of another run of Cobra cradles? :D

I'm still not clear on whether a torque arm/diff brace/any other kind of brace is neccessary with the retention of the stock diff? Is the stock diff mounting points not able to cope with the extra torque? thanks!

In smaller batches, sure. :)

A torque arm's only purpose on an FD is to supports the nose of the differential, since an IRS differential doesn't move with the suspension like a solid axle differential. Since that's the case, one isn't necessary if you use an alternative mounting setup like the Cobra differential does.

Mazda used a "powerplant frame" to rigidly connect the diff to the transmission and engine to reduce slop in the drivetrain and improve response to changes in throttle position, since there are less bushings to compress/expand. The C5 and C6 Corvette do the same thing, but with a "torque tube". Once again, not really necessary with a rigidly mounted differential.

Oh, this is what I want to hear, I keep missing them because I am so on and off with my car. How many people this time, I frequent the forums more now so I should be able to get in on one.

My fabricator would like to do between 5-10 at a time, but we'll do an engine cradle GB before the next Cobra IRS GB to give him a break. :)

Jim could you elaborate a little on the motor mount differences btwn 'vette and the f-body ones? I'm familiar w/the f-body ones, but not so w/the 'vette's. Any potential engineering flaws in design that you'd like to share or show..? Thanks..

Bring out the whips and chains, no break for him.

Sigh, either way, I'm in for both.

Corvette mounts are aluminum brackets or "stands" (one is shown in the picture below, just in front of the exhaust manifold) which bolt to the block and then rest flat on "biscuit" style rubber bushings. They make it a lot easier to drop in an engine since they can be installed/removed after the engine and transmission are already in the car, and the flat mounting surface makes it much easier to use spacers to adjust the position of the engine vertically, if necessary. They also make it possible to provide more than one engine mounting position on the same cradle.

The F-body "clamshell" mounts are probably fine structurally, but they're bulky, heavy, and because of the design, not as easy to drop into cradle mounting points or easily installed/replaced after the engine/transmission is in the car. They also require mounting brackets on the engine cradle that get in the way of things like turbo exhaust manifolds. :)

https://www.rx7club.com/attachment.p...d=148329&stc=1

This guy thinks of everything. Does it effect the alternator (f-body).

The accessories are far in front of the motor mounts. They only look close because of the angle of the picture. Note how far even the SBC conversion mounts are from the front of the block...

https://www.rx7club.com/attachment.p...d=147267&stc=1

hmm., thanks for the explanation. so solid mount brackets from the looks of it? I have no experience w/vettes but most solid mounts seem to transmit a good deal of engine noise and vibration to the car, is this the case w/these? Is there a rubber doughnut perhaps sandwished between mount and chassis? What's the going rate for these$$? may consider using them when fabbing the fc mounts..

Again thanks.

just re-read your statement, forget what I said..

Jim, is there or could there be in what you envision a provision in this tranny brace to tie the differential in too - basically provide the support that the torque arms from Hinson and Granny's provide - in case we should want to keep the OE diff pumpkin?

Since a local friend may be going to the dark side also, I'll probably be looking into a support that allows retaining the stock diff, but without a torque arm. Of course, you could always use someone else's torque arm with my engine cradle and save me the hassle. :)

Jim,I like your old avatar better

Given that there is no longer any reference to your feelings about the torque arm 'solution' on TC, I take that it is now OK to use one? :D No, I'd rather have an option. ;) Could you share the rationale against torque arms, BTW? I really want to know why you are against it.

It was no longer accurate. :)

Don't need one. :)

The differential in an IRS car is fixed and is not intended to move. The torque arm in a Camaro is required by the live axle/differential which cycles up and down with the suspension. On an FD, all the torque arm (or PPF) is doing is locating the front of the differential for correct pinion angle. That job done, it's just extra weight and takes up room in the transmission tunnel that could be better used for the exhaust system.

My main objection to the torque arm is that it mounts to the transmission brace and acts like a long lever on that brace, which is why people have had the mounting pads for the transmission brace tear off the floor pan. They're only tack-welded on, with some seam sealer around the edges, and were only meant to work laterally as a brace system to increase the rigidity of the transmission tunnel. They were never meant to support the load of the transmission and differential.

Thanks, very clear now and makes sense. :)