I wanted to introduce myself and show some of the complete work I've done so far.
I'm Nick from NE Ohio. I've always loved the idea and style of the GTM and finally purchased a Gen 1 GTM that was never started by previous owner. I believe this is car #164. I like to do things efficiently and sometimes a little outside of the box and the plans with this car are not different. This will not be a big budget build but rather use the right combination of inexpensive parts to make a fun car.
As of this post I have hung the suspension and ran the front brake lines. Started to pull the wiring and painted/mounted some of the aluminum.
The brake setup uses c5z calipers along with adapters and Baer rotors that were sourced from a Mallet corvette that came into a local salvage yard.
The aluminum panels are painted using a fine texture truck bed liner which I think looks great and gives a refined look.
Engine and Trans plans are as follows.
5.3L lm7 (Yes this is iron block but it was sitting around the garage and is perfect for boost.) The cost of this engine will offset the costs of turbos and related pieces that are needed vs buying new crate engine.
Porsche g96 trans from 99-04 911. This trans is much less expensive even after buying another adapter than the hard to find g50.
I've already learned a lot from the short time I've been here and look forward to progressing the GTM build.
Renegade racing has a few 996 911s making 5-600 as well as the boxster variant of the trans(its nearly identical just inverted from 911). I'd like to see mid to high 500s on low boost (7-9 psi) for most driving and then 700 on 16 or so. I havent decided yet if it will be e85/flex fuel or pump/race gas. Will the trans hold that?...maybe if I'm careful lol. My current issue is deciding how I want to handle the fueling. The early c5 tanks don't have many options for internal fuel pumps. Have any of you guys done an external in-line pump?
One solution you may want to consider for fueling is this drop-in solution for the later OEM C5 tanks. Not sure if you are that far along that you have the older style tanks mounted.....but....if you can use the later C5 tanks this is a very slick (and reasonably priced - like $500) solution for up to 800+HP NA - 700HP Boosted.
Using this in my tanks now that Shane is installing a Schwartz Performance 675HP LS7.....needed more fuel.
Luckily bumped into this unit when I was searching for options. Lingenfelter just released this new unit at SEMA last November. Pretty slick solution if you can use those tanks!
I have converted mine to an external pump. I hacked up the existing plates and added -8 AN bulkhead connectors on both sides. Only using one side now for my mild h/c setup, but dual pumps in the future could be easily added. Here are a few pics of my return style system.
I actually had new aluminum plates made which would make for a cleaner install without the marine grade jb weld plugging up the unused holes, but i have not gotten around to putting those on. Next time i remove the hacked up stock plates, ill put on the new plates i had made. No pics of those at the moment, but they are nothing special. Just round blank aluminum plates without any holes in them yet...
Did you leave the float attached for the fuel gauge? Is there any sort of sump or tube on the other side of your plate? or does it not actually pick up all the gas at the bottom of the tank?
I actually made a plate for the pumpless tank, similar to what Shane sells for the tank crossover. Maybe Ill add another fitting for another pump on that side . I like your setup and I guess I guess I could always add a Holley hydramat if I cant pickup all the fuel from just a fitting. Thanks!
I left the stock float on the (now) right side tank on the same plate where my fuel pump is on. The gauge reads that. I tried to place the bulkhead fitting as low as possible on the plate, but there were many constraints since i was using the stock plates to do this. My plan eventually is to use the new plates for the crossover like shane does, and also for the fuel pump outlet fittings. At that time i would place the fuel pump fittings as low as possible which should be lower than i have it now. Where i have them now is not the lowest, but it will also help to prevent any debris from clogging up my filters which may have settled at the bottom of the tank. If i were doing the whole system from scratch, i would consider just using a Tee in the middle of the crossover line and use that for the fuel pump source, but my crossover was already made and in place so i didnt want to redo it.
For those that forgot to unlock the steering before removing the column from the Corvette. I was able to unlock it by putting power to purple wire, ground to black. Then jumping power or ground to one of the other two wires in the column. Saved me from tearing the whole thing apart.
A pic of the roller has been added to my gallery in first link.
Beware those push lock fuel connectors. If they do not have something other than the plastic clips to retain them THROW THEM AWAY. We found out the hard way and had $80k worth of fire damage. It's a $15 part that has new designs readily available. It is just not worth risking using those fittings. Also, if you can identify the company that made those I would bet dollars to doughnuts that the company has a new design and would happily swap them out for you.
Have you considered building the 5.3 vs turbo? For about the same money you could make 500+ N/A hp. (without even stroking it - bore it and you can use 5.7 pistons.) Less weight, less heat, less complication. You don't have the option to turn up the hp like with the turbo, but you really can't turn it up much without doing a stronger trans, clutch, axles anyway. Just a thought. That's what I'm doing. I haven't built mine yet, I'm still looking at a forged 383 stroker kit...>
The 5.3 just kind of happened because I already had the motor sitting around. It's not all that suited well for NA. You might as well have aluminum block ls2,3,7 etc to start with if you want 500 NA. There is something about the sound of twin turbos and the way that the power is delivered that makes me want to go that route. Not to mention the advantages of having differing power levels at the flip of a switch. Ultimately without spending 10k+ on a trans, you're limiting factor probably wont be the engine.
Have you considered building the 5.3 vs turbo? For about the same money you could make 500+ N/A hp. (without even stroking it - bore it and you can use 5.7 pistons.) Less weight, less heat, less complication. You don't have the option to turn up the hp like with the turbo, but you really can't turn it up much without doing a stronger trans, clutch, axles anyway. Just a thought. That's what I'm doing. I haven't built mine yet, I'm still looking at a forged 383 stroker kit...>
I don't know why you don't think the 5.3 isn't good for n/a power. With just a cam swap it can make 420hp. The GTM will do 0-60 in 3.2 secs. with that. There shouldn't be any difference between the iron blocks and aluminum blocks when it comes to making power at these levels. I guess your referring to the displacement. I'm either going to stroke the 5.3 (with ported stock heads or aftermarket heads) or get a 6.0 and use l92 or ls3 heads, I just haven't decided. Either way it should make good power for a 2500 pound car. These cars already have problems with heat in the engine compartment, turbos just compound the problem. Using an iron block and going turbo just adds that much more weight. I understand about the sound and being able to run different tunes with the push of a button, but that's (imho) not worth the other issues I mentioned earlier. It's ok if we disagree, everybody likes different things. Just thought I'd throw the idea out there.
By the time you put heads/cam on them you are at the cost of an aluminum LS motor.
You must be talking flywheel HP(and even then I'm skeptical) because you aren't making 420 at the wheels with just a cammed lm7.
There is a difference in the iron/alum blocks with sleeving when you are talking 600+
Heat I can deal with and weight is no issue when you can turn the boost up.
By the time you put heads/cam on an iron block motor you're at the cost of an aluminum motor with much less hp. You'll need to put heads/cam on the aluminum motor to get to the hp where the iron block is then. An aluminum block doesn't make more hp than an iron block, it has nothing to do with moving more air. Maybe you know something I don't? There are multiple examples of the (crank) hp levels I'm referring to all over the internet many from reliable sources. Fuzzyjk (Kalstar on the other forum) has an aluminum 5.3 with a cam making this kind of power in his GTM. Either way It's your car do what you want with it...
I think there may be some miss communication. We essentially are saying the same thing. The iron block lm7 that I have is a bit different then the l33 aluminum 5.3. Those have better heads and can achieve 400+ with a cam. The lm7 will make abut 40 less due to heads, cr, intake etc. When you are talking about boost and 600 wheel hp the iron block 5.3 is farther ahead than say an ls1 or ls2 due to heavier castings and thicker sleeves. 500 hp wheel probably would cost the same to make with any of the motors but if I want to turn it up to 700 it will be easier with the iron 5.3
Yeah the 799 or 243 are the ones to have and they have a smaller combustion chamber than the 5.7 heads bumping up the compression. I'm pretty sure they put them on both iron and aluminum block engines. As far as the block though there's no difference when comparing aluminum and iron as far as hp. I get that you want the turbos and that's cool, I was just saying you can build a competent n/a motor from any of these with the right components.
The only downside to any in-tank setup is the royal PITA to R&R a fuel pump if it goes bad for any reason. The process of extracting a pump requires taking your interior apart- taking out the pass. seat, pulling up carpet/ vinyl, drilling out rivets to get the panel off, then you get to start doing the actual work on the fuel tank. After going thru all that BS once, that was enough for me to go the external route. But hey, to each their own :icon18:
Agreed. Pro's & Con's to each approach. I had previously R&R the fuel pump module in the later C5 tanks and it was a real PITA....but I was able to do it without removing the tank (just the passenger seat/tank cover and a LOT of patience....)
Thought about going the external route with the upgrade to the LS7, I just like the comfort of knowing that all that stuff (pump/regulator/filter/etc.) is in the tank staying cool, fuel level float and hooks up are OEM, and one simple line to the fuel rail is all I have to worry about.
Like many things (everything???) on a GTM....many ways to skin that cat.....
A few updates:
More pictures added to the album in the original post!
Enginge is back from getting freshened up. Ring gaps opened up, btr cam kit installed, trunion upgrades, holley oil pan, arp rod bolts, headstuds, and ls9 headgasket installed. Ive got the holley HP ecu and wiring harness that will control the motor and clean up the wiring.
G96 transmission is installed. I used kitcarchassis.com's adapter kit, and a spec stage 3 clutch.
I cut off the brackets on the subframe and notched out the first tube. I ground down the bosses on the back of the transmission and then welded on new brackets to the subframe. I still plan on using the boxster s 6spd shifter, along with metric cables and metric ball ends.
Fuel system is nearly done. I installed an lpe/walbro intank pump on one side and created a bulkhead plate for the other tank that has the -12an crossover fitting as well as another -6an outlet. The outlet runs to a prefilter, then another walbro 255 (inline) which gets Y'd in with the intank pump on the other side to a post filter then the rails. This external pump will turn on via the holley ecu when in boost. I took Crash's recommendation and purchased the push-on to an fittings with the screw in safety. I used them on the outlet of the tank. Thanks for the advice!
The turbos have arrived and I'm deciding how to mount them and whether or not this will require any sort of flex pipe/bellows for the up pipes to the turbos.
Two random questions I've run into:
What do the brackets do on the rear subframe near the rear of the transmission (the ones that form a triangle shape and have the two holes in the top(bottom of attached picture))? They are in the way of the cable shifter and I would like to know if they can be removed.
Maybe I'm missing something but is there any sort of metal behind the engine cover in the interior(between the fuel tank covers and below the rear windows aluminum)? Or is it just that leather wrapped piece of fiberglass?
Two random questions I've run into:
What do the brackets do on the rear subframe near the rear of the transmission (the ones that form a triangle shape and have the two holes in the top(bottom of attached picture))? They are in the way of the cable shifter and I would like to know if they can be removed.
Maybe I'm missing something but is there any sort of metal behind the engine cover in the interior(between the fuel tank covers and below the rear windows aluminum)? Or is it just that leather wrapped piece of fiberglass?
I believe those brackets/holes are for the exhaust mounts. Some folks use them, some folks make a bracket that attaches to the trans to accommodate engine movement.
And no, you're not missing anything. No metal in the waterfall cover, just some plastic and vinyl between you and the spinning engine accessories and belts. Makes it all more exciting!
Thanks for the info regarding the G96 install! I will be installing the G96 in spring, so I am always looking for advice. It looks like a good solution how you modified the subframe!
If I remember correctly, those brackets were to mount the crossmember of the old Porsche G-50 trannys. I still have one of the brackets laying around somewhere.
Cheers, Jeff
Thanks everyone for the information. I was able to come up with turbo placement after throwing the body on and taping up the diffuser to see how much room I have. I've also ordered some off the shelf cables and will be updating everyone on how well those work for the transmission .
Starter update: I had a clearance issue with the generic starter that came with my adapter kit, it was just a bit to long and would not clear the BB c5 headers. I had a difficult time find a starter that engaged the flywheel in the same location as the adapter plate isn't machined large enough to accommodate the different mounting positions of aftermarket ls starters. I did finally settle on the B&M startek ls starter (same as powermaster 9409). Big thanks to summit for letting me pull down about 7 different starters, buy 4 and return 3 of them haha
I was able to get most of the hotside tacked together. I chopped the old 3 bolt mounting flanges off of the headers in favor of vbands. I added vbands after a few of the bends to make taking it apart easier. Things are getting tight back there and as much as I would love to see those shiny stainless pipes, i think everything is going to get wrapped so I don't melt my starter and shift cable.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Factory Five Racing Forum
3.3M posts
50.6K members
Since 2002
A forum community dedicated to Factory Five owners and enthusiasts. Come join the discussion about performance, racing, conversions, modifications, troubleshooting and drivetrain. We discuss MK4, GTM, 818, Type 65 coupe, roadsters, and more!