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Old 10-18-2012, 08:53 AM   #1 (permalink)
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New race car direction = LS7 in a Lotus; please read and comment

Winter is coming in Canada.... just like summer in Texas, one cannot go racing. So racer's minds turn to race car building and refinement....

I know Henessy did it, but it is NOT a race car.

I have done a Honda K20 conversion. I am happy with the result. I am afraid that the transaxle is the weak point and will give me problems. Then I am faced with an upgrade expense of L11k = USD$18k minimum for EliseParts or more from Xtrac, etc.

If my target is 500 to 600hp with potential for 800 tractable, reliable hp, then why not extend the wheelbase and mount a longtitudonal drive-train.

For the 600hp, I would need:

1. Used LS7 motor $6k. I would make sure it came with a clutch and all dry-sump gear. All internals are forged. There is lots of aftermarket.
2. Cam, exhaust and fitting $3k.
3. Porsche, Mineola, Rockland, Ricardo, etc. transaxle $10k + slave/concentric cylinder.
4. Labor to extend the rear sub-fram. Mine is all tube-frame, already, so I just need to work the lower a-arms.
5. Labor to extend the body. Mine is all custom, so maybe I just make a 'straight' insert in front of the wheel wells.
6. Custom axles from drive-shaft shop, $1k, since I already run Corvette hubs.

I am at 20k. Almost the same as the transaxle! If I want to get more power, then a small blower, including the stock ZR-1 will do nicely.

Now what is the downside:

1. Another 200lbs in the rear of the car.
2. What is the impact of longer wheelbase?
3. I have to make sure that my price for transaxle is correct. I have just 'seen' stuff float by on the internet...

Looking at this, I think about the Honda investment:

1. Sleeved Motor (long block) $5k
2. Trans $2k
3. Clutch CC - $2k
4. Head work and parts $4k - probably overkill.
5. Turbo/BOV/WG $2.5k
6. Dry sump $3k
7. K-pro $1k
8. I got a good deal on the mounting kit with the chassis.
9. Custom axles $1k

Again, about $20k. I certainly think, I could recover a fair chunk of it to put forward to the LS7!

Am I crazy? or foolish?

At this point it is just a thought,

Anton
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Old 10-18-2012, 08:57 AM   #2 (permalink)
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LSX FTW! I wouldn't even think twice if I could tackle the job myself.
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Old 10-18-2012, 09:28 AM   #3 (permalink)
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not crazy or foolish, if you have the time and money and talent. and if your gonna spend it anyways... i vote Vette

the wheelbase and any weight changes just mean development time on sorting the suspension. i would think there is a good rear suspension you can 'hack' into the new rear subframe. i would think a 'monocoque' cage into the chassis, and some triangulation.. would be prudent.

hey, if you're gonna go.... go big!
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Old 10-18-2012, 09:29 AM   #4 (permalink)
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Go for it. I've wanted to do the same since 1996 (Elise GT1)
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Old 10-18-2012, 09:33 AM   #5 (permalink)
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Few comments.

A) IMHO the GM LS-series is a great engine (series of engines). I wouldn't hesitate for a second to use it if I had the ability.
B) Unless you are really tied to the "wow" factor of the engine code, there is no inherent reason for the LS7. I work at a dyno shop where the bread and butter is LS. The LS7 is great, but not for the money. I personally really like the a lightly built LS3 which can do around 500whp and mid 400ft-lbs with basic modifications on a stock shortblock. Hell you can easily get to 450whp+ with an unopened longblock (albiet not stock cam). LS2 IMHO is the king of bang-for-the-buck especially if you plan to build it anyways.
C) The "dry sump" on the LS7 (and versions of the LS3) is pretty crappy. Leaves something to be desired for sure. Its better than a standard wet-sump but its not a good dry sump. Figure on going with a real dry-sump
D) The added wheelbase is a MUST for a car with that kind of power/torque. Even with the turbo Honda setup you would likely want it. A short wheelbase, mid-engine with a lot of power/weight really needs a long wheelbase to keep it from wanting to switch ends all the time.
E) I'm sure you are leaving out LOTS of little expenses of swapping to the LS.

I personally would do a dry sump on a mild bolt-on LS3 (intake, headers, exhaust, cam, tune). Nearly unusable amounts of power, while keeping it very close to OEM reliability. NA powerband, response, and consistency would be amazing!

And but not least.... you mention "Race car", but what do you mean by that. What race series are you considering building something like this for?
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Old 10-18-2012, 09:44 AM   #6 (permalink)
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re: Race series

There are regional races in CASC just like SCCA. There is a 1 hour race series that used to be called CAnada Challenge Cup. The GT1 class is unlimited. The rest are time brackets.

Thre are local 15/20 min sprints, but they are no fun.

This is all just for fun...

Anton

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Few comments.

A) IMHO the GM LS-series is a great engine (series of engines). I wouldn't hesitate for a second to use it if I had the ability.
B) Unless you are really tied to the "wow" factor of the engine code, there is no inherent reason for the LS7. I work at a dyno shop where the bread and butter is LS. The LS7 is great, but not for the money. I personally really like the a lightly built LS3 which can do around 500whp and mid 400ft-lbs with basic modifications on a stock shortblock. Hell you can easily get to 450whp+ with an unopened longblock (albiet not stock cam). LS2 IMHO is the king of bang-for-the-buck especially if you plan to build it anyways.
C) The "dry sump" on the LS7 (and versions of the LS3) is pretty crappy. Leaves something to be desired for sure. Its better than a standard wet-sump but its not a good dry sump. Figure on going with a real dry-sump
D) The added wheelbase is a MUST for a car with that kind of power/torque. Even with the turbo Honda setup you would likely want it. A short wheelbase, mid-engine with a lot of power/weight really needs a long wheelbase to keep it from wanting to switch ends all the time.
E) I'm sure you are leaving out LOTS of little expenses of swapping to the LS.

I personally would do a dry sump on a mild bolt-on LS3 (intake, headers, exhaust, cam, tune). Nearly unusable amounts of power, while keeping it very close to OEM reliability. NA powerband, response, and consistency would be amazing!

And but not least.... you mention "Race car", but what do you mean by that. What race series are you considering building something like this for?
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Old 10-18-2012, 10:22 AM   #7 (permalink)
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do it
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Old 10-18-2012, 11:19 AM   #8 (permalink)
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Quote:
Originally Posted by ageshelin View Post
There are regional races in CASC just like SCCA. There is a 1 hour race series that used to be called CAnada Challenge Cup. The GT1 class is unlimited. The rest are time brackets.

Thre are local 15/20 min sprints, but they are no fun.

This is all just for fun...

Anton
Ahh ok. Yea obviously it would definitely have to be some form of an unlimited class. Downside being of course that you will get thrown in with a bunch of purpose built race cars.

If you go through with it (and don't mind), start a build thread. I think a lot of us would be interested in seeing it progress. And many would be able to lend some advice.

Also I would definitely recommend keeping the stock PCM and tuning it. There are quite a few tuning software packages for the stock PCM, but I like HP tuners the best, and would highly recommend. There are lots of "universal" harnesses out there for either DBW or mechanical TB as the Gen III and Gen IV are used in lots of custom hot rods and the like.
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Old 10-18-2012, 11:41 AM   #9 (permalink)
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well its a great idea if you have the means and skill to pull it off.

I cant help but think any of the myriad of tubframe/kitcars/racecars designed for ls engines would make more sense. something like an ultima gtr or similar. I am guessing the "small things" will end up putting you way over budget, but that is just speculation as I have never taken on such a huge project.
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Old 10-18-2012, 11:58 AM   #10 (permalink)
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Originally Posted by aschen View Post
well its a great idea if you have the means and skill to pull it off.

I cant help but think any of the myriad of tubframe/kitcars/racecars designed for ls engines would make more sense. something like an ultima gtr or similar. I am guessing the "small things" will end up putting you way over budget, but that is just speculation as I have never taken on such a huge project.
^^ This is a really a good point.

I do think the OP is glossing over a lot of the "little" work/money that is needed. And also agree it likely makes the most sense to simply change to a purpose built race chassis that is already designed around the small block chevy.
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Old 10-18-2012, 12:16 PM   #11 (permalink)
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The Ultima GTR is where I plan on going.
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Old 11-09-2012, 04:22 AM   #12 (permalink)
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I'd love to see it. I'm still scratching my head as to why no-one has really delved into small V8 conversions for the Loti. Hennessy excluded for obvious reasons.
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Old 11-09-2012, 04:50 AM   #13 (permalink)
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I'd do the Ultima, RCR or similar, but ...

Check out how Chapparal made chassis for their Can-Am cars; they were really boxes of fiberglass and not that complex in construction. Suspension geometry is another matter, but you could definitely create a 1960s Can-Am car in your garage. Our Elige chassis are really minature aluminum tub cars. The RCR is really a pre-engineered version of our cars with a Chevy and sounds like what you (we) want.
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Old 11-09-2012, 04:22 PM   #14 (permalink)
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Thing is also, you don't necessarily have to step into new-age production engines. A 7L V8 is a massive hunk of a motor to try and squeeze in.
There are smaller V8's out there, just look at what Ariel did with the Atom, or the 2L V8 in some of the Caterhams... both making 500 and 340bhp respectively!
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Old 11-09-2012, 05:01 PM   #15 (permalink)
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re: Another (kit) car

The thought has crossed my mind. I even talked to Fran at RCR before I bought this car. He said that I could go faster for less $$$ (with RCR). He was probably right

There is RCR, FactoryFive GTM, Mosler and a few others. Mosler has been the most successful, as he was banned by every sanctioning body for being too fast.

The trickiest part of the car is suspension and I was concerned with the amount of time/resources/knowledge spent by the kit car builders. Perhaps, unduly so...

I have raced some Ultimas and was not impressed. Maybe it was the driver(s).

My other goal was to build a car that weighed under 2000lbs. I thought this was hard to achieve with mild steel tubing. Nobody offered moly or aluminum, except Lotus.

So, Lotus it was. The next reason not to go with any of those mid-engined cars is that I already have a Lotus. I invested a lot in it and an engine swap is much more cost effective than a car swap. Am I missing something?

Anton

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I'd do the Ultima, RCR or similar, but ...

Check out how Chapparal made chassis for their Can-Am cars; they were really boxes of fiberglass and not that complex in construction. Suspension geometry is another matter, but you could definitely create a 1960s Can-Am car in your garage. Our Elige chassis are really minature aluminum tub cars. The RCR is really a pre-engineered version of our cars with a Chevy and sounds like what you (we) want.
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Old 11-09-2012, 05:20 PM   #16 (permalink)
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re: Motor

The whole point of my post is:

1. I already have a very strong 2L motor. It makes 750hp.
2. I need a good transaxle to go with it. One way to side-step this issue is to do motor/tranny swap. (or buy a 'real' transaxle or hope that the Honda does not break because the car is too light...)
3. A V8 is not so big or heavy. The only motors that offer a significant weight saving (based on charts that can be found on the internet) are:
a. Mazda rotary
b. Purpose built racing motors e.g. Indy V8's, Hyabusa-based V8's probably fall in this category.
c. Modern Subaru 4-cylinder. Surprisingly light or am I mistaken?
d. Modern aluminum 4-cylinders are marginally lighter and not that much smaller.

Anton

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Thing is also, you don't necessarily have to step into new-age production engines. A 7L V8 is a massive hunk of a motor to try and squeeze in.
There are smaller V8's out there, just look at what Ariel did with the Atom, or the 2L V8 in some of the Caterhams... both making 500 and 340bhp respectively!
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Old 11-09-2012, 06:34 PM   #17 (permalink)
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go for it.....
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Old 11-10-2012, 03:28 AM   #18 (permalink)
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A longer wheelbase will get you a little more top-end stability and a little less point-ability…but not nearly as much as increasing the front castor angle.
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Old 11-10-2012, 06:32 AM   #19 (permalink)
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it is not clear for me what you are looking for? The faster dragster or a fast road race car?
If it is for road race track, I think that you focussing too much on the engine itself.

In regards of your cost estimate, put twice at minimum for a set-up with a transaxle (40k minimum instead than 20k). Just for my car, I have more than 20k dropped in the powerplant, plus another 20k on the car itself.

If you are asking the question and your cost estimation let me think about your project. If you ask call for saying that you are not a specialist. If you are not a specialist, the project will be too big and you will need a lot of time, money, and trial and error when the car will start.

If you are doing road race track, why so much power? You will be alone if you are a good driver if the car is set correctly in term of handling.

Assuming that the car have 600 hp, maybe. The cost to drive the car will be very high. At that point, just buy a car with more muscle like a Vette.
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Old 11-10-2012, 10:40 AM   #20 (permalink)
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re: objectives

I road race. I have been for a while. I even won a few regionals.

These are thoughts on drive-train. I am well aware of sauspension and training opportunities.

Out here there are a lot of good tracks (Mosport) and drivers. Therefore, some hp is a pre-requisite for keeping up

The objective of a drive-train (engine+tranny+axles) is :

1. Power curve. (before I get killed with torque, do not forget that I said 'curve' and power=torque*rpm/5250).
2. Initial investment and TCO.
3. Reliability (related to 2).
4. Weight

Anton


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Originally Posted by elise/europa View Post
it is not clear for me what you are looking for? The faster dragster or a fast road race car?
If it is for road race track, I think that you focussing too much on the engine itself.

In regards of your cost estimate, put twice at minimum for a set-up with a transaxle (40k minimum instead than 20k). Just for my car, I have more than 20k dropped in the powerplant, plus another 20k on the car itself.

If you are asking the question and your cost estimation let me think about your project. If you ask call for saying that you are not a specialist. If you are not a specialist, the project will be too big and you will need a lot of time, money, and trial and error when the car will start.

If you are doing road race track, why so much power? You will be alone if you are a good driver if the car is set correctly in term of handling.

Assuming that the car have 600 hp, maybe. The cost to drive the car will be very high. At that point, just buy a car with more muscle like a Vette.
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