LS series, CT525/LS3 engine questions...

[F22 RAPTOR]

On the CT525/LS3 Chevrolet engines:

Does anybody know what sort of valve angle the heads have?

How about port flow for the CT525/LS3 heads?

Are there any versions of the LS series engine that utilizes a distributor?

[giffordracing]

dont really no..but here is some picts of a lsx with a distributor in it

http://baldwinengines.com/index.php?...ine&Itemid=101

[stockcar5]

There is no factory option to use a distributor.

not true
http://www.crateenginedepot.com/stor...P1452C119.aspx

[dynoman14]

Just thought I would add a perspective from somebody who has owned, built and run these things almost 10 years ago with fuel injection and all of that hoo-haa...it sucked !!!

Be prepared to purchase a laptop and software to work on the fuel injection and ignition, and have somebody at the track with you that is a GM Certified Technician to troubleshoot the problems that will come up. The guys GM brought to the track from Michigan used to run and hide about 30 minutes into practice and that ain't no joke.

The first couple years in ASA when they converted from that "so-called" Super-Expensive V-6 that you could build for $25K, and GM was gonna come along and save the world with the LS-1 ASA Crate ( it ended up costing almost $15K and then you had to buy all new headers, water pumps, fuel pumps, belts and drives, clutches and bellhousings... )...after the first year about 1/2 of the original ASA racers got fed up and quit, engine were overheating, e-boxes were failing, engines were blowing, and there were some teams with GM help that walked the dog all over everybody. Jimmy Johnsons' team Herzog Motorsports won for a couple years then it was Kevin Cywinski, then Joey Clanton. Traction control was rampant and so was the ability to tune +100hp into the Delphi Command box...hmm was that Jimmy Johnsons' sponsor at Herzog???

I still have a couple engines that I purchased from Cywinski / Country Joe Racing, oh yea they bought the stuff from Herzog anyway I purchase a bunch of the engines and put 8 in street cars and kept the Best 2 for personal projects. They made 525 from the factory, were tunable to 575 pretty easy and with the flip-flop box you could get almost 650 out of them.

HEAD FLOW
The L-92 ( LS3 ) family of ports will go over 300 cfm out of the box, CNC'd by from Chevy almost 350cfm, cnc'd by somebody good 375-400cfm. The LSX family of ports are close to 350cfm out of the box and over 400cfm CNC'd from GM and by someone good close to 450cfm. ( All of these are 28" Numbers )

As a point of reference I paid $8500 for a set of SB-2 Heads ported by Darin Morgan and 5 years ago they were about the best you could get at about 415cfm @25". ( Equal to 440cfm @28" ). That was with 275-280cc ports. The engine at 358" ( Big bore / Short stroke / Short Rod / Short deck block ) 12:1 with a mild roller 276-282@.050", 750 carb, Sunoco 100 made about 835hp and 550#tq.

If you want to see what a 1000hp LS engine runs like watch the "Pinks" show from Atlanta and see how fast that Corvette goes. A lot of dyno time and money went into that project more than a year before the race.

The cathedral port LS heads are doing their big numbers with 250cc's and less and you can buy a pair from GM ready to make 800hp for about $3500 pair delivered to the house ( bare ). The work quality is awesome, the valve Job is either Serdi or Newen depending on the shop the come out of and the castings will hold up to 1000HP+NA and 1300HP+ with a couple shots of laughing gas. That is how 10" tire street cars are running almost as fast as NHRA ProStock cars now.

I am all for the new engine and new heads, but I'll take a carburetor and distributor any day...why do you think they outlawed carburetors in wine and cheese racing??? Cause the fuel injected cars could not keep up.

JMO

[F22 RAPTOR]

I'm gonna just lay all my cards on the table and see what comes of it. I've been impressed with how well Ronnie Johnson has been running utilizing his CT525 against open comp supers. Most tracks in my area can't handle the kinda HP the big guys engines can put out anyway so I got to thinking... The CT525 does well in the super slick, but doesn't have quite enough to make the show when there is tack, so. My thinking was what if I could build something that performed similarly(torque curve) to the CT525, but had just a lil' more umph. I was thinking about an engine in the 400 cube range(4.125 bore X 3.75 stroke) built relatively mild, say 600-650HP, but good torque. Does this make sense to anybody? I figured with the added cubes I wouldn't even need the latest and greatest heads because I don't wanna turn it too hard anyway. Just some thoughts I had, but any input would be appreciated. I'm not saying I want to build an LS series engine, but rather a traditional SBC that mimics the CT525's better attributes, I mean it seems to work well.

As far as fuel injection and brain boxes, I'm not opposed to them, but I don't wanna take a step backwards either...

[F22 RAPTOR]

Yes, the motors need a little more to run on a fast track. Problem is the CT525 is the only way you can use the motor. You can't run the coil/harness setup under a general open motor rule. So, it's either 525 or nothing.

I don't want to build or run an LS series engine or CT525 per say. With the rule changes that SAS and other series have made to further handicap the CT525, I was thinking of building a typical SBC, but with CT525 characteristics(ie the torque curve), but with a little more power(600-650HP). Any thoughts on head and cam selection in a 400 cube engine(4.125 x 3.75)? Would I need a raised cam? Would 23 degree heads work or would I need to go 18 or further?

[Matt49]

Stockcar5: Maybe you should spend more time reading, rather than posting an attempt to prove someone wrong. Hell, you didn't even read that part category did you?

"LS-Series-Gen-III-LS1---LS6---LS7---LSX"

Do you see LS3 anywhere in there? Didn't think so. Not all LS-series parts are interchangeable among other LS motors.

Please get your facts straight next time. THERE IS NO FACTORY OPTION TO RUN DISTRIBUTERS ON LS3 MOTORS.

Well I DID do some reading and according to Brad Hibbard (Race1) via his website, the part that Stockcar5 referenced will work just fine.
http://race-1.com/new-ct525/

I think you owe stockcar5 an apology.

[stockcar5]

in lieu of an apology i'd just like him to check facts before typing. this way it wont waste someones time by giving them wrong infomation.

thanks for clearing that up matt.

[HEAVY DUTY]

I have talked to 2 guys who have a lot of experiance with the ls motors and they both said to stay away from the distributor drive because they were not very reliable.It is a shame that the sanctioning bodies want to stay in the stone age.If you run the MSD 6LS box and the coil packs, you have oil pressure shut down and temp shutdown and anti knock sensors to back the timing off if the motor starts to detonate to protect the engine.All that stuff comes on a junk yard engine.

[dynoman14]

Truth,
I totally understand fuel injection as I was given an 1989 Z-28 to work with at the dragstrip using a brand new 5-D software system called DFI. After figuring out all the problems with changing a MAF System to Air Speed Density, DFI sold the system to GM and Accel and that sprung the ASD, which is ok for High Performance use but MAF is still the best to use on the street for drivability, weather conditions and fuel changes from supplier to supplier. Made some great money on the deal got racing paid for for 2 years and got to keep the car. Still got the original laptop, Flash Ram box, software and fuel injection system.

Here is the bottom line, unless you are running 24Hr LeMans to save fuel stops...cutting back on fuel cuts back on HP. There is no such thing as saving 25% fuel without cutting 25% HP. Fuel injection does not increase the VE of the engine, and fuel injected cars do not make more power per mass of given fuel than a carburetor. It takes roughly a 1/2 # of fuel per hour to make 1HP so if you plan on making 500hp with any kind of fuel delivery it is going to take 250# of fuel an hour.


F-22,
I a not sure about your logic on building an engine with a similar torque curve to the 525Crate but another 100HP??? Are they that good??? GM did not just figure out a magic formula to make a torque curve. If you do want to build a similar engine you will have to make sure your ratios of bore / stroke / rod length are similar, compression ratio, and that you have way enough airflow to get the job done. Large torque curves are indicative of having way more airflow than you need

When I build a race engine the first thing I look at is the fuel that is allowed and that will tell you what you can do with the engine. Is it fast burn, slow burn is it open to your choice. The next step is to look at the air-fuel delivery system which to me is every thing above the head gaskets ( and of course the fuel pump ).

Once you have establised the maximum airflow delivery of that system you will know the HP ( roughly 2hp per cfm with the head, intake and carb strapped to the flow bench ). Now that you have the power level determined you can put together an air pump ( below the head gaskets ) that will adequately handle the power you throw at it. The torque curve is determined by the camshaft and how it opens and closes the valves. Bore and stroke have an influence on where the peaks occur as they will dictate how quickly the air is pumped out of the top end. Big cubic inch rolls torque way down , small cubic inch will turn up higher having the opportunity to make more high end rpm at the loss of bottom end torque.

I have seen several GM 604 crate heads ( couple hundred at least and I flow every one that comes thru my shop ) in the past 10 years and in stock form they flow 230-255 cfm. You do the math on that and you can see why some folks look like they are shot out of a cannon.

The one thing the LS port has going for it is it is tall and skinny, with a cathedral top and it flows about 20% more air for the same port volume. Tall skinny ports maintian a better fuel charge than standard Chevy ports although short wide ports usually get it done better than tall skinny ports. You just have to look back about 20 years to the Feuling designed Quad-4 Oldsmobile port. With minimal work he got the little 4 banger up around 700hp NA and about 200mph with the mirrors on ( about 50hp extra at 200mph ). The following year he did a few aero adjustments and added a small turbo and almost hit 300mph ( 286mph I think ) but the car was too boxy, and too short of a wheelbase and was all over the place. I think the calculation for that coeffiecient of drag on that car was around 1100hp stock block and heads.

Bottom line, build your engine for maximum torque and HP for a given combination and gear the race car accordingly.

There are a couple things that can skew the numbers some like changing rod length, which changes piston speed and instantaneous acceleration, and dis-proportional cam lobes and assymetrical intake and exhaust lobes but that is probably better left for another discussion. Honda has kinda taken that cam stuff to a new level with the V-tec even though Nissan came up with it first but had no success marketing their system as it was more VVT ( Variable Valve Timing ).

[F22 RAPTOR]

Truth,
F-22,
I a not sure about your logic on building an engine with a similar torque curve to the 525Crate but another 100HP??? Are they that good??? GM did not just figure out a magic formula to make a torque curve. If you do want to build a similar engine you will have to make sure your ratios of bore / stroke / rod length are similar, compression ratio, and that you have way enough airflow to get the job done. Large torque curves are indicative of having way more airflow than you need

When I build a race engine the first thing I look at is the fuel that is allowed and that will tell you what you can do with the engine. Is it fast burn, slow burn is it open to your choice. The next step is to look at the air-fuel delivery system which to me is every thing above the head gaskets ( and of course the fuel pump ).

Once you have establised the maximum airflow delivery of that system you will know the HP ( roughly 2hp per cfm with the head, intake and carb strapped to the flow bench ). Now that you have the power level determined you can put together an air pump ( below the head gaskets ) that will adequately handle the power you throw at it. The torque curve is determined by the camshaft and how it opens and closes the valves. Bore and stroke have an influence on where the peaks occur as they will dictate how quickly the air is pumped out of the top end. Big cubic inch rolls torque way down , small cubic inch will turn up higher having the opportunity to make more high end rpm at the loss of bottom end torque.

I have seen several GM 604 crate heads ( couple hundred at least and I flow every one that comes thru my shop ) in the past 10 years and in stock form they flow 230-255 cfm. You do the math on that and you can see why some folks look like they are shot out of a cannon.

Bottom line, build your engine for maximum torque and HP for a given combination and gear the race car accordingly.

I see. Thanks, I think the CT525 is pretty good, at least it seems to be pretty good in the slcker situations, even without a weight break and taller spoiler. I sometimes get lost in your responses, are you saying the 604's have good heads? How do they compare to other after market 23 deg heads? I assume they are 23's...