Supercharged Chevy LS7 as a Race Engine
#1
Posted 18 March 2006 - 02:24
My question is how viable a race engine could this smallbock be? Specifically, how powerful could this engine be if it were mated with a supercharger under the requirement that it lasts say 1200 miles under race conditions (i.e. practice/qualifying/racing). I understand some of the internal components might have to be exchanged... How extensive would the modifications be to get this engine to handle the strains placed on it? Also, how would such an supercharged LS7 engine compare in weight and cost to something that is currently being produced by Cosworth for the Champcar series?
The reason I ask this is because I'm trying to a fantasy formula (on paper) and I would like to have a large displacement engine that puts out heaps of hp and torque without incurring tremendous costs. I think that the LS7, thanks to its small block desing and aluminium contstruction, might be a great platform. Would it be capable of 1200+ hp without too much fuss or am I way off?
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#2
Posted 18 March 2006 - 06:20
The LSX blocks bores are hard to get and keep round and the head bolt pattern isn't great. The bores really move around a lot even after just 650hp NA for 1000 miles even after they were prepared perfectly. You can actually hear a degree of "interrupted hone" when you freshen it in the initial couple of thounsandths. I would say to go 1200 race miles, a more conservative forced induction application estimate would be 800 hp, keeping engine speed very low redline 6500 RPM or less.
World Products has its aftermarket LS1 based block and heads for sale starting at the end of this year. It was supposed to be available right about now but as usual there have been delays. This option should hold force inducted 900hp for 1200 race miles IMO. I would still keep engine speed as low as possible. I would go with turbocharging instead of supercharging too.
I think for a forced induction build, at a bare minimum you're going to have to spend 30K USD, very likely closer to 60K USD if you get pure race components and good labor. Into the realm of custom one-off pieces to copy exactly the actual 24 hour hour type stuff (processes and components), closer to 120K USD. I am currently building a milder NA 700hp C5R version of what you seek to build and am just about ready to assemble. Total cost has been 40K USD so far and that is just parts alone, almost all of them at prices not available to the public. Also doesn't include labor since I am doing the all the porting, machine work and assembly myself.
Cosworth XFE is around 310 lbs, your engine will probably end up roughly at 460 lbs including turbo wastegate, piping, intercooler, so about 150 lbs heavier.
You might want to look at aftermarket aluminium small blocks from Brodix or Donovan. Older generation smallblock parts are slightly cheaper and it all adds up to savings. If you can afford an extra 100 lbs and the vehicle is mid engined, you might want to even look at a cast iron block because they are very strong and will last multiple freshens, holding 900hp easy. You can get CGI versions of any cast iron block from Dart now that are even stronger.
#3
Posted 18 March 2006 - 22:15
Having said that I believe the Lexus V8 engine has formed the basis for some powerful engines, although I think combination of 1200 hp and 1200 miles is way outside the envelope.
#4
Posted 18 March 2006 - 22:41
The cost estimates I provided in my post above were already assuming just plain block and heads with other required parts bought. I did not calculate starting with the LS7 crate engine and then replacing all the internals. Doing so would add about 7-9K USD.
#5
Posted 18 March 2006 - 22:54
However, I should clarify my position. I'm not seeking to put an engine into any kind of car. The excercise I am doing (mostly for my own amusement) is designing a theoretical car (much akin to a Champcar). I've done a rough sketch of the chassis, and I had planned on mating it with a supercharged LS7 engine. Lacking any real knowledge of engines, I wanted to get some feedback concerning the viability of my choice for a race engine (that could put out 1200hp and last an equivalent amount of miles). Cost and weight are also issues.
I really like the 7 liter engine size, which has that alluring number of 427 cubic inches. Would a purpose built block be more economical and effective, then?
#6
Posted 18 March 2006 - 23:01
If you're going to endurance race, yes you should go with a ground up block. It won't be more economical, but it will be more effective.
#7
Posted 18 March 2006 - 23:20
Originally posted by Greg Locock
If you want to end up there (1200 mile race engine) why would you start from here (cost reduced heavily optimised production engine)? Any savings on the initial price will be eliminated as you replace every single part that is over-stressed.
Having said that I believe the Lexus V8 engine has formed the basis for some powerful engines, although I think combination of 1200 hp and 1200 miles is way outside the envelope.
Today you can buy a complete IRL engine (without electronics) such as the Oldsmobile Aurora for around $8000. Ok, the engine is used and in parts but its output closer to 700 hp and it's ready to be used as a stressed member of the chassi. Assumed that one changes the piston-rod assemblies and machined the block for steel liners this type of engine should probably be good for more than 1200 hp with forced induction even if not for a full 1200 miles. Compared with a Lexus engine you also get a special block casting with a dry sump lubrication system. You also get race cams, titanium valves, a ported head and so on. This is also a very light and compact engine, the weight as NA is just around 130 kg, turbocharging adds probably around 20 kg or so.
The only downside is the supply of spare parts, eventually it will be hard to find new main castings such as block and heads.
Originally posted by D. Heimgartner
I understand some of the internal components might have to be exchanged...
Usually it's the other way around; some might not need to be changed. This of course implying that most parts must be changed, leaving only few stock parts (mainly the castings, which usually must be modified in other ways).
#8
Posted 19 March 2006 - 02:28
You will also notice that the driver sits more upright, providing more usable crushspace in the front of the car and also providing a more natural seating arrangement. The entire chassis is more broad shoulder then other open wheel cars. Thus, the bodywork extends much closer to the wheels than other formula cars like Champcar and Formula1, where the suspension arms reach a couple feet or more.
Any comments, constructive criticism, compliments would be welcome. And of course, I had considered the supercharged LS7 engine for this theoretical race car. But some of you have pointed out the weaknesses of that decision, and I certainly appreciate the other suggestions made so far. Again, due to the lack of downforce this car has, it would need a great amount of power to accelerate it out of turns.
#9
Posted 19 March 2006 - 09:49
#10
Posted 19 March 2006 - 10:12
By comparison, a stock 1993 Toyota Supra engine has a peak BMEP of 321psi, and that's with lots of backpressure (cats, small turbos) and the relatively higher FMEP of an I6 (compared to a V8), and it still meets OEM durability requirements. So in that light, I don't think that 1000+bhp from 7L is THAT much to ask durability-wise is it?
#11
Posted 19 March 2006 - 10:19
The more useful measure of thermal stress (as opposed to mechanical stress) is probably bhp/in^2 piston area, and a 1200bhp LS7 has almost twice the piston loading of a stock Supra engine... Quite a big difference!
#12
Posted 19 March 2006 - 17:57
Originally posted by hydra
1200bhp from a 7L engine is "only" 171bhp/L . Assuming a peak power rpm of 6500rpm this gives us a BMEP of 342psi @ peak power, and probably around 375psi at peak torque...
By comparison, a stock 1993 Toyota Supra engine has a peak BMEP of 321psi, and that's with lots of backpressure (cats, small turbos) and the relatively higher FMEP of an I6 (compared to a V8), and it still meets OEM durability requirements. So in that light, I don't think that 1000+bhp from 7L is THAT much to ask durability-wise is it?
The Supra engine is quite stout and well designed. The LS7 is an exercise in packaging- max cubic inches in the smallest. lightest package possible- n othing wrong with that, just not something to base a race engine on.
#13
Posted 19 March 2006 - 18:05
#14
Posted 19 March 2006 - 18:22
Originally posted by bobqzzi
The Supra engine is quite stout and well designed. The LS7 is an exercise in packaging- max cubic inches in the smallest. lightest package possible- n othing wrong with that, just not something to base a race engine on.
I understand what you're trying to say, but aren't all race engines designed to squeeze as many cubes out of the smallest, lightest package possible? :-)
#15
Posted 19 March 2006 - 18:53
Originally posted by hydra
I understand what you're trying to say, but aren't all race engines designed to squeeze as many cubes out of the smallest, lightest package possible? :-)
The Supra isn't a race engine, and most engines are designed as road engines then homologated.
#16
Posted 19 March 2006 - 20:44
#17
Posted 20 March 2006 - 07:08
Originally posted by D. Heimgartner
Well, as for the mission, imagine what is expected of a Champcar: temporary and permament road courses as well as ovals.
you mean it will have to turn left and right?
#18
Posted 20 March 2006 - 19:57
#19
Posted 20 March 2006 - 20:36
Question 2: Where did the 1200 HP level come from? It's *way* excessive. Champ cars at their present power and downforce level can spin the tires at over 100 mph. The only thing in the world that is on a road course and accelerates like it is an F1 car. Now you want 80% more power and 10% of the downforce. It not a reasonable combination, regardless of what tire you put on it.
Question 3: How much do you want to spend?
Comment: Your front wings are pointed in the wrong direction.
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#20
Posted 20 March 2006 - 20:45
Katech would be a good source of information about the durability of LSx type engines for racing use.
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John
#21
Posted 21 March 2006 - 05:30
Regarding your first question, this exercise came about because I was very critical of the new Elan01, Champcar's next generation chassis. I blasted the design of the car for various reasons, and then I was challenged to come up with my own design. What you saw earlier in the thread is my crude attempt at chassis design. (Thanks, btw, for pointing out the wing mistake.)
Regarding question two, I should have explained also that my chassis design is significantly heavier than the current Champcar or the new Elan01. I believe that those two cars weigh in at about 1600-1700lbs, engines included. My design, which would weigh something like 2000-2100lbs, would be more broad snouted and more broad shouldered. Thus, because I envision a chassis roughly 25% heavier than the Champcar chassis, I sought a corresponding jump in hp. While it is the case that the current detuned Cosworth V-8 only puts out about 750hp, a few years ago the engines pushed closer to 950hp. I wanted a similar power2weight ratio as that of those earlier Champcar beasts as driven by JPM, for example. I also understand that 1200hp is somewhat excessive, but if you consider the amount of horsepower put out by the turbocharged Formula 1 cars of the mid 1980s, the fact that my design weighs roughly 25% more than a current Champcar, and that this design will have to impress people with raw power, then you might see why I chose the 1200hp figure.
Regarding question 3, I would like to have corresponding costs to that of the new Elan01, which is believed to be about $375,000 for the chassis and something like $750,000 to $1,000,000 for a one year engine lease. So to answer your question, this would have to be an engine format that could produce 1200hp at about $1,000,000 for 16-18 races. Again, I am quite partial to the 427 number; however, if you or anyone else could suggest a better engine formula, then that would be great.
#22
Posted 21 March 2006 - 07:16
a NA 427 - either LSx or SBC-based - producing 800bhp at no more than 7000rpm would be a cool choice for a racing series (can you imagine what it would sound like? ), and it needn't break the bank either.
If you still insist on impressing people with raw power, I would suggest a similar rat-based motor...
You're probably going to need a custom gear$$box to deal with all this torque though
#23
Posted 21 March 2006 - 07:37
Frankly, I don't think your proposal looks very impressive aesthetically speaking. Why not go with a modern interpretation of the stunning pre-war Mercedes W125 and Auto Union C-type?
- 750kg
- 6" wide wheels
- NO aero (although you would want to design for zero lift)
600-800bhp (doesn't really matter with the tires you've got)
Its a crazy idea - I know, but I'm sure there are few board members on here who wouldn't love to see something like this see the light of day
#24
Posted 24 March 2006 - 02:18
#25
Posted 25 March 2006 - 12:00
Originally posted by D. Heimgartner
Fat Boy:
Regarding your first question, this exercise came about because I was very critical of the new Elan01, Champcar's next generation chassis. I blasted the design of the car for various reasons, and then I was challenged to come up with my own design. What you saw earlier in the thread is my crude attempt at chassis design. (Thanks, btw, for pointing out the wing mistake.)
Regarding question two, I should have explained also that my chassis design is significantly heavier than the current Champcar or the new Elan01. I believe that those two cars weigh in at about 1600-1700lbs, engines included. My design, which would weigh something like 2000-2100lbs, would be more broad snouted and more broad shouldered. Thus, because I envision a chassis roughly 25% heavier than the Champcar chassis, I sought a corresponding jump in hp. While it is the case that the current detuned Cosworth V-8 only puts out about 750hp, a few years ago the engines pushed closer to 950hp. I wanted a similar power2weight ratio as that of those earlier Champcar beasts as driven by JPM, for example. I also understand that 1200hp is somewhat excessive, but if you consider the amount of horsepower put out by the turbocharged Formula 1 cars of the mid 1980s, the fact that my design weighs roughly 25% more than a current Champcar, and that this design will have to impress people with raw power, then you might see why I chose the 1200hp figure.
Regarding question 3, I would like to have corresponding costs to that of the new Elan01, which is believed to be about $375,000 for the chassis and something like $750,000 to $1,000,000 for a one year engine lease. So to answer your question, this would have to be an engine format that could produce 1200hp at about $1,000,000 for 16-18 races. Again, I am quite partial to the 427 number; however, if you or anyone else could suggest a better engine formula, then that would be great.
Kevin Kalkhoven have earlier said that he wanted a new chassi that is more F1 like while probably sticking to a small displacement turbocharged engine. The Panoz DP01 seems to be just what he wants; the car is slighty smaller, lighter and has a F1-style raised footbox. The current champcars are about 1550 lb, but the new Panoz DP01 brings that down to something like 1400 lb, only slightly heavier than a F1 car (with ballast weights).
The 2.65 litre V8 engine that is used in champcar could easily be redesigned for a higher power output, 1200 hp or more is no problem, but with increased costs naturally. Compared to production based engines this engine is very light and compact, it's also a stressed member of the chassi. Since regulations have only allowed one turbocharger I think you could make packaging easier by going to two turbos instead, then a turbocharger placed in the clutch/gearbox housing is no longer needed.
Turbocharging was used in champcar as early as late 1960, with power outputs of more than 1000 hp during the seventies, this with 2.65 litre/162 cui engines. The only reason for the lower engine outputs that followed was the restrictions on boost pressure.
Lighter less powerful cars are usually prefered over heavier more powerful ones for safety reasons. Even though lap times can be similar, the lighter less powerful car won't go as fast on the straights and there will be less energy involved in a crash, most likely also less fuel (given that refueling is allowed or not allowed in both cases).
#26
Posted 26 March 2006 - 03:02
#27
Posted 28 March 2006 - 09:41
#28
Posted 28 March 2006 - 16:29
Great stuff there... I think the use of a supercharged M-B engine is a great idea and would add lots of cachet to any racing series (Small Blocks, even really powerful ones, are a dime a dozen)
The engine should have no problem with 600-650bhp either. Just remember to keep your tires skinny... The objective isn't to lap the 'ring in under 7 minutes, but rather provide drivers with a test of skills and the spectators with lots of thrills
#29
Posted 28 March 2006 - 16:46
After all, you gotta fill that gorgeous long hood somehow!
#30
Posted 28 March 2006 - 17:17
Originally posted by shaun979
JE, do you think they subsequently re-designed or evolved the engine design to be lighter since it needed to make less power? How many miles do you think a 1200hp turbo 2.65L champ car engine will go before requiring rebuild? What do you estimate rebuild costs are? I think they are quite high since not just anyone can do it.
Doesn't the teams pay about a million dollars for the use of an engine during one year? In that sum I think 13 rebuilds are included so each rebuild can't be too expensive. By the way, I saw an ad where Cosworth CK engines where for sale, rebuild costs was there said to be about £10,000, I can assume that a ChampCar engine is slightly cheaper to rebuild than a F1 engine. The cost for each rebuild will most likely also depend on what is changed, I mean sometimes perhaps changing gaskets, piston rings, timing chain, bearings and similar is enough but at other times components such as block, heads and crankshaft must be replaced, but probably not as often though. Say that for example block and heads are good for one season, the crankshaft for half a season, pistons and valve springs for two events and so on.
The newer less powerful ChampCar engines are i bit lighter I think, but not much. They are also a bit simpler, for example the pre compression injection system have been removed and the turbocharger have been replaced with a cheaper non ball bearing one. I would assume that they have improved reliability and reduced the cost rather than decreased engine weight to match the new performance.
If power is increased to 1200 hp by using higher boost pressures (avoiding higher engine speeds) I don't think it will be that hard on the engine if some modifications are done; compression ratio must be decreased somewhat, slightly stiffer cylinder liners should probably be used along with stronger pistons. Possibly a stronger exhaust valve and exhaust valve follower may be needed. This higher output will naturally also increase the cooling demand.
Rebuilds are probably needed after one or two events if safety margins are good enough.
#31
Posted 02 May 2006 - 04:20
#32
Posted 02 May 2006 - 09:13
Originally posted by J. Edlund
I can assume that a ChampCar engine is slightly cheaper to rebuild than a F1 engine.
The current F1 engines (last 10 years or so) are AFAIK not rebuilt. If they last the two races they currently are supposed to, they will end up in the scrap bin.
Possibly the rev-restricted V10 used by Toro Rosso will get some element of rebuilding.
So the costs for "re-building" is the cost of a new engine every second race.
#33
Posted 05 May 2006 - 02:37
#34
Posted 05 May 2006 - 03:53
Look at those gaping giant four valves, an oxygen aphrodisiac.
-Cylinder walls in revolutionary TWAS technology
-Vertical intake and exhaust ducts
-Four-valve technology with two overhead camshafts and bucket tappets
-Dual-length variable intake manifold in magnesium technology with two interior throttle flaps
-Continuous camshaft adjustment on the intake and exhaust sides
-Close-coupled catalytic converters
-Oil-water heat exchanger
-Solid aluminium crankcase with bedplate and closed-deck design with cast-in steel components
Cylinder arrangement V8
Cylinder angle 90o
Valves per cylinder 4
Displacement 6208 cc
Bore/stroke 102.2/94.6 mm
Dist. between cylinders 109 mm
Compression ratio 11.3 : 1
Output 375 kW/510 hp at 6800 rpm
Output per litre 60.4 kW/82.1 hp
Max. torque 630 Nm at 5200 rpm
Torque per litre 101.5 Nm
Maximum engine speed 7200 rpm
Weight (dry) 199 kg
Power-to-weight ratio 1.88 kW/kg
Sexy as hell.
#35
Posted 05 May 2006 - 05:23
If only they had this as a wallpaper.
#36
Posted 05 May 2006 - 17:25
Before you start to reply keep in mind what M-B would charge you for a crate engine..
#37
Posted 07 May 2006 - 05:00
Originally posted by Powersteer
As much as I love to hate pushrod engines, the LS7 is definately an execption
I hate them to. Why do they stick with that 1800 tecnolegy?
What about a chevy502 as a race car engine? ad this heads and you should produce nice hp http://www.araoengineering.com/
#38
Posted 07 May 2006 - 11:14
Personally, I think a well-designed pushrod engine is more than enough for a production "V" engine. Most pushrod engines you see today have a redline of 6500rpm or so - not much lower than most all-singing, all-dancing quad-cam 4-valve engine, which seem to be so-equipped due to marketing reasons really. You don't need all those cams and valves if you're not going to be turning more than 7000rpm. Compare the LS1/2 with equivalent engines from the "thoroughbred" manufacturers and you'll see what I'm talking about. BMW 4.5 V8 : 333bhp, Infiniti 4.5V8 : 340bhp with its fancy titanium valves. Audi 4.2V8: 300-something bhp, etc, whereas the lowly pushrod LS1 has 345bhp... So strike one, fancy DOHC engines. Remember, I haven't even considered the 405bhp LS6 here, which would have even more of an advantage...
Each of the import engines mentioned above typically weighs around 425-450lbs, whereas the LS1 weighs 380-400lbs. Strike two, fancy DOHC engines. Don't even get me started on packaging volume... Have you ever seen a pushrod V8 next to a DOHC V8? The difference in size is obscene!
As for manufacturing cost, I don't even bother with this one... Strike three fancy DOHC engines, yerrrrrr out!
I've said it before and I'll say it again. DOHC 4-valve V-engines only make engineering sense if you're chasing maximum output and (very) high rpms, which most OEMs are certainly not. Why go through all the trouble and expense if you only want 75bhp/L and 7000rpm? Its just an image/marketing thing really.
The reason pushrod engines have such a bad rep, the way I see it at least, is because of the despicable boat anchor engines (and cars now that I think of it ;)) the big three used to make between roughly 1972 and 1992. After all, its not very easy to like a 5.7L V8 that only makes 180bhp (160 in California), or even worse, a 7.4L V8 with 220bhp. Shameful really...
#39
Posted 07 May 2006 - 14:45
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#40
Posted 07 May 2006 - 18:44
Its the image and marketing that makes you think it is - in this case at least...
#41
Posted 07 May 2006 - 20:14
#42
Posted 08 May 2006 - 03:45
Originally posted by desmo
Have to agree Hydra. For Vee engines in production cars, pushrods and 2 valves per cylinder still make good sense even today. For an inline type, DOHC 4 valve designs may make better sense.
#43
Posted 08 May 2006 - 07:28
Originally posted by hydra
Umm.. an extra 3 camshafts and 2 valves/cylinder don't exactly put an engine on the bleeding edge of high tech
Well to some, it is merely adding 3 cams and 16 more valves. So what is the bleeding edge of technology??
#44
Posted 08 May 2006 - 08:22
Adding more of an existing component doesn't really make an engine high-tech. If Ferrari released an engine tomorrow with 4 oil pumps and 8 water pumps would you call it high-tech?
Things like dry-sumps, variable intakes, VTEC/VANOS mechanisms, all-aluminum construction, and maybe even multiple valves are what I would call "cool-tech", but not necessarily high-tech
#45
Posted 08 May 2006 - 14:16
Originally posted by hydra
Things like ion-sensing ignition, MMC or composite engine internals, infinitely variable valve-lift mechanisms like BMW's valvetronic, and a bunch of other stuff I can't think of right now... Basically GENUINELY innovative technologies that are cutting edge.
Adding more of an existing component doesn't really make an engine high-tech. If Ferrari released an engine tomorrow with 4 oil pumps and 8 water pumps would you call it high-tech?
Things like dry-sumps, variable intakes, VTEC/VANOS mechanisms, all-aluminum construction, and maybe even multiple valves are what I would call "cool-tech", but not necessarily high-tech
Can you show me a mass production V8 that has all those, I would love to see it?
#46
Posted 08 May 2006 - 18:06
I'm with Hyrda though - there's some neat/cool stuff like the Zed Oh 6, but I haven't been thoroughly thrilled by a new car in......... ....... .......a long time. By their very nature, production cars become pedestrian and old-hat for everyone 'cept the person in the driver's seat.
#47
Posted 11 May 2006 - 00:38
#48
Posted 11 May 2006 - 02:56
[QUOTE]Originally posted by Canuck
I'm with Hyrda though - there's some neat/cool stuff like the Zed Oh 6,
#49
Posted 11 May 2006 - 05:41
Similar thing happened in Spain at a McDonalds - British couple trying to order tea with their breakfast, gettin' madder and madder that the staff only spoke Spanish. Go figure.
In my experience native english speakers like myself are notoriously uni-lingual. Hell, the low-man-on-the-pole that pushed a broom at my shop in Dubai spoke no less than 5 languages - Arabic, Farsi, Urdu and 2 Indian languages. He understood english and was slowly learning to speak it too.
And it'll always be Zed. Zee is just so...lightweight
#50
Posted 11 May 2006 - 12:08
Originally posted by Canuck
And it'll always be Zed. Zee is just so...lightweight [/B]