What were everyone's engine choices, crate or DIY?

[Jeff W]

I'm pricing out engines to begin costing the SL-C, and they're available partially dressed (intake and ignition), long block, crate, or DIY. An LS470 runs about $12k before changes like dry sump, fuel pumps, alternator, etc. and pricing out full aluminum LS kits is going to run pretty close to the same once you start tossing in components capable of handling fair RPMs and outputting my desired 550-600HP. Figure the LS470 is a pretty fair price, but I wouldn't mind taking a smaller CID and slapping a turbo on it - but those jet engine noises come with a price tag too!

What have most folks done? Chevy Performance crate engine?

 

[Howard Jones]

It's all about the use.

If you intend to take it to the track, even a few times a year then the engine rotating assembly needs to be balanced as an assembly by a qualified machine shop. Engines that are production built (ALL crate engines) are not balanced. They are part-specific weight selected. That means all the pistons, pins, rods, are selected individually in a range of weight groups, the crank machined to given tolerance, and then assembled. Tolerance stacking can then take the rotating assembly far out of the range of what would be considered a machine shop custom balanced engine. A qualified machine shop should be able to hold a less than 2 gram out of balance fairly easily with less than 1 gram as a target for the whole assembly. This would include your choice of the flywheel, clutch pressure plate, damper, and belt pulley.

Street rods, streetcars, or whatever you want to call them will never see engine revs remain above 3500-4000 RPMs for 30 mins at a time making 50 -100% of its potential HP. This is what happens on track if you are trying to maintain a quick pace. A street engine will spend the majority of its life at idle or at cruise speeds. They also will spend nearly all their lives making less than 25%, or less, of their potential HP. IMHO, nobody makes a street/track engine that will survive track use. BUT a track use built engine will be very happy on the street if the compression ratio and cam timing are carefully considered.

So what to do? Crate engines are a great way to get all the parts in one box. The crate 535HP LS chevy is just about right as far as hp goes and comes with a controller and associated parts that seem to work for most people. If I was doing this again I might just do that except take it apart and send the rotating assembly and block to my chosen shop to get it balanced, prepared, and reassembled with ARP rod bolts, While it was apart I would have the heads looked at, a really nice valve job done, some port cleanup and valve springs checked.

Now you have a motor that will run like a top for the car's lifetime.

Of course, you can do all this yourself and build a monster motor. Just be SURE you have someone who can tune it for you. I have been on record here for years taking the position that 500HP is plenty (maybe too much) for a 2500ish pound streetcar. Of course, it's your money so you are free to do whatever turns your crank.


That's my 2cents worth.

Weighing in on Balancing Work - Engine Builder Magazine

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[Kyle]

Said it before and I’ll say it again, junkyard LS. Does that mean one that’s been sitting out in the rain? No....an 80k mile, vehicle pull out, L92 can be had for $2500, $1.5k more for cam, intake and corvette accessories, all new. You can either use the stock harness and make it stand alone for cheap, or put your money you save into a nice Holley system and tune it yourself. These motors can take a TON of abuse. A gen IV bottom end is good for up to 850. None of that matters though if you don’t have a good transaxle to put the power through. If you can turn a wrench this can all be done at home, even porting the heads.

Everyone on here starts tossing all sorts of oil coolers, dry sumps, surge tanks etc for mostly street cars, those things just aren’t needed.

I think Howard’s points are spot on when he’s talking about the life of an engine in a certain RPM range, most of these cars will never see the abuse that a track car will. So putting a 10k engine just doesn’t make sense to me. Most people are building this car for the joy of building, why skimp in the engine? Take one apart and build it too.

 

[Jeff W]

Two perspectives, both requiring disassembly and further work. I think that points the needle in favor of a DIY engine build with a scavenged harness and ECU.

Thanks

 

[Larry L.]

I have been on record here for years taking the position that 500HP is plenty (maybe too much) for a 2500ish pound streetcar.

I agree with everything you said...up to the above! ;-)
THERE I have to agree with whoever said, "There's no such thing as too much horsepower...'just too little traction"...or something close to that!

 

[Jeff W]

Missed that little bit of 500HP perspective there. Dropping the HP to sub-550 range has a significant drop in cost. 525HP engines are everywhere, the 550+ ones tend to cost more probably due to a lower demand. I'm going to have to do some research on building a higher HP motor that can withstand a few RPMs, the last one I built was a 302 for a muscle car which topped out around 290-300.

 

[Jeff W]

EDIT: I'm glad I'm asking these questions now. Building an engine to a target horsepower has never been something I've needed to consider. It's always been "How much can I do to this engine without it coming apart on me?" and the horsepower result being what it is.

 

[Howard Jones]

Here's a good number to remember. Now before I say it of course I need to qualify it a bit. There is no universal perfect equation for what will work for a street-driven motor. There are just too many variables to account for. BUT here it goes. 1.4 HP per cubic inch on pump gas. That maximum hp number will get you an engine that will last years and not require you to spin it to huge rpm numbers, run compression ratios that require race gas, replacement of valve springs, and other valve train pieces constantly or other extreme building requirements.

So what to do. First, since the are no rules for streetcars, make it big, as far as CI's go. Then build down on exotic components to achieve that 1.4 number. A 300CI making 425hp is the same thing as a 400CI 565hp as far as reliability goes. The theory goes that you could build a +100,000 mile 500hp motor that runs on pump gas, doesn't overheat, idles nice and smoothly, and requires little or no maintenance with the exception of oil changes.

My ideal street engine for a 2500 pound mid-engine car like an SLC or GT40 and others would be a 400 CI 10.5 to 1 compression, hyd roller cam (no more cam than required) 500hp motor. It will last your lifetime. This is easy with an LS and pretty cheap too. Remember to balance it!

It will also not require you to spend a huge amount of money on the rest of the drive train.

Here's another number. You will need to spend about 2 times the cost of your motor on the rest of the power train. $8k motor = $16K clutch, flywheel, gearbox, driveshafts, CV's, stub shafts, cooling systems, oiling systems and fueling systems etc. That number will approach 3 to one above 800HP, with maintenance intervals continuing to be reduced to near racecar levels. The bigger the motor the less engine maintenance you can expect at a given HP level but the rest of the drive train doesn't know what is turning it, just how hard. An 800hp engine and power train could easily equal the rest of the car as far as cost goes.

Don't forget that somebody will need to tune your custom monster. $$$$$$$$$$$$$$$$

Above 800HP all bets are off................there are no tires anyway..................good luck.

 

[Doc Watson]

What were everyone's engine choices, crate or DIY?

I wanted an 'original' engine, I don't mean a numbers correct 289 hi-po from 1965/66 but a 4.7 ltr (289 cu. in.) engine with 48ida's. In order to pass the UK requirements for registration if the engine is pre 1975 then all that is required is a 'visible smoke test' as part of the emissions.

So a good friend (Thanks again Frank!!!) had a spare 1972 Mexican block which I now have as a basis for my engine build. I will be assembling the engine myself and will leave the buying of the crank, rods and pistons to nearer the time that I can start it with fuel, electrics etc installed.

I have 1966 289 heads which will be reworked and am looking for about 350-400HP from the engine with maximum 10:1 comp ratio. Block has been hot tanked, skimmed, bored 20 thou over with notches in the skirts (if I want to go 330 cu. in. stroker) and the oil plugs have been replaced with screw in plugs.

The crank will probably be a 289 billet BUT with internal balancing which will involve the addition of Mallory to the crank, this cannot be done yet as I will obviously need the rods pistons and rings for bob-weight calculations.

Heads will be ported and although Chevy 'larger valves' will fit (just) in the 289 heads I will stick with the standard size valve with uprated springs and solid roller lifters hoping to get up to 7000rpm. I cannot do the machining so all parts will be acquired ready to fit into the engine when (and if) the time comes.

Its going into a mk 1 road car so engine size and look are important to me although for sure this will not be an FIA approved engine.

Sure I could get MUCH better flow rates using modern heads at probably less cost than to buy/refurb a tired set of 289 heads but am trying to produce a mk 1 as close as possible to the original car....

 

[Jeff W]

Thank you. This is valuable info and well said. I’d already planned on buying the full Graziano and clutch completion kit from RCR, so that cost is covered in my build spreadsheet. I’m also looking at pathways to an aluminum LS3 6.2 build, it seems to be the best balance of costower. 2k block, 2.8k rotating assembly, + 1.2k heads, then all the extras (valves, machining, balancing, etc).

 

[Randy V]

Weight (or lack of) is also Horsepower.
Your 2500# car with 450 HP will be a worthy opponent for a 550 HP 3500# car (Dodge Viper)
With most DOT spec tires, you’ll be hard pressed to put more than 450 HP to the ground.
I echo some of the earlier comments about drivability. Not much is worse than trying to drive a an ill-tempered racecar on the street with the chucking and chugging associated with attempted smooth clutch engagement. Keep your compression at or below 10:1 so you can burn pump gas. Camshaft profiles with centers that are less than 110 are a royal pain to tune for part throttle operation and quite honestly, while they may sound neat, they drive like crap.

 

[Jeff W]

After looking around I figure a 6.2 LS3 is going to be the starting point. I just need to figure out what vehicle I can find that will have one in it with an aluminum block, if that's cheaper than buying a block outright. Swap in some good-quality forged internals, get them balanced first, and then try to understand a higher RPM valvetrain assembly with whatever heads I end up with. I don't see much reason to not use the stock EFI and intake, but maybe a little carbon fiber eye candy with a bigger throttle body might be fun for an otherwise plain engine.

 

[TroyK]

I want to go the LS3 crate route as well, but I'm hard pressed to talk myself into it. It seems like that puts the SLC's overall performance barely into the conversation with current mass production peers, like the C8s for example, while not even coming close to what's possible otherwise.

What are people's thoughts on the current hypercar engine trends, disregarding they hybrid portions, as a guide for how current engineers have thought about good street manners with even higher performance. Koenigsegg, McLaren, and even the leaked specs for the upcoming C8 ZR1 and Zora are all trending towards a 4.0-5.XL twin turbo v8, 9:1 compression, and run on 91 octane without water/meth kits or anything exotic. A competent traction control + gear sensitive boost control also seems like it would prevent you from roasting tires in low gears even in a very light car. All of these are intended for the street and put down the power through DOT tires, which I presume are probably Pilot Sport Cup 2s if anything.

 

[Joel K]

For my build, the goal was to register the car in my home state of NJ. To do this, it either needed to have a 1969 or earlier block to avoid emissions testing or pass emissions requirements for the year of the engine. So I went the crate engine route, but with a production ECU with full EVAP and emissions capability. The logic being a production ECU has the ability to be ODBII compliant with 4 O2 sensors and full EVAP. To Kyle’s point I could have grabbed an engine and ECU out of a used car, but wanted to go new.

I like GM engines so had the choice of an LS or LT stock equivalent. LS-3, LS-7, LS-9, LT1, LT4. I did not think the higher horsepower LS-3 equivalents could pass ODBII so stuck with a stock equivalent. All these would have really good street manners and in theory with a standalone harness and stock ECU they should pass emissions. I chose the LT4 for the 650 horsepower, lower height supercharger, and variable valve timing which makes a nice smooth idle. I don’t plan on tracking the car, but this should be a heck of a street car with the LT4.

I’ll know by this time next year if I can get it to run and pass ODBII. I will admit, it has been a lot of work and planning to accommodate the LT4.

 

[Jeff W]

Well, that's something I hadn't thought of... I guess I'll have to make sure I get an ECU with whatever LS I end up with. On that same subject, did you put catalytic converters in your exhaust? Seems like that'd be part of the whole smog thing, though lots of the SL-C builds that I can actually see some of the header setups on don't seem to have them.

 

[Jeff W]

I want to go the LS3 crate route as well, but I'm hard pressed to talk myself into it. It seems like that puts the SLC's overall performance barely into the conversation with current mass production peers, like the C8s for example, while not even coming close to what's possible otherwise.

What are people's thoughts on the current hypercar engine trends, disregarding they hybrid portions, as a guide for how current engineers have thought about good street manners with even higher performance. Koenigsegg, McLaren, and even the leaked specs for the upcoming C8 ZR1 and Zora are all trending towards a 4.0-5.XL twin turbo v8, 9:1 compression, and run on 91 octane without water/meth kits or anything exotic. A competent traction control + gear sensitive boost control also seems like it would prevent you from roasting tires in low gears even in a very light car. All of these are intended for the street and put down the power through DOT tires, which I presume are probably Pilot Sport Cup 2s if anything.

I agree with what you're saying, but this car setup doesn't afford all the bells and whistles that keep the power safely to the ground in the supercar family. So no matter the engine type chosen it's just not going to be able to keep the wheels stuck to the pavement for best acceleration. Just a few of the things missing in the DIY supercar that the SLC is, so managing the power to the wheels is strictly up to the driver. Throwing this thing up against cars like the Koenigsegg really isn't fair.

 

[Joel K]

Well, that's something I hadn't thought of... I guess I'll have to make sure I get an ECU with whatever LS I end up with. On that same subject, did you put catalytic converters in your exhaust? Seems like that'd be part of the whole smog thing, though lots of the SL-C builds that I can actually see some of the header setups on don't seem to have them.

Hi Jeff, yes, I will be adding catalytic converters.

 

[Davidmgbv8]

I have bought a salvage yard 1999 Ford Explorer 302. Changing the cam to a comp cam XE274HR 512 lift 114 lobe separation 264 duration. Now I picked this engine for the GT40P heads... unfortunately they were cracked so I will be going with AFR165. This combo should yield 350hp on the stock 9:1 compression. This is where I want to be as I am replicating a street car, my only deviation is going with a 4bbl EFI so my build mimics GT40PR. So if anyone out there has a Sunbeam Tiger air cleaner for cheap I would like to talk to you..... back up plan is the EFI 8 stack Webers. Interesting reading on here lately that the 4bbl flows more than the Weber Independent runner.

 

[TroyK]

Just a few of the things missing in the DIY supercar that the SLC is, so managing the power to the wheels is strictly up to the driver. Throwing this thing up against cars like the Koenigsegg really isn't fair.

I disagree with this, depending on your state's requirements for engine management options. A current generation Megasquirt has quite a number of features to help with keeping the tires hooked up: launch control, multiple methods of traction control, gear sensitive boost, multiple maps for street/sport/track, etc. You could also get the same features for more $ from a more mainstream ECU if you're not willing to go the Megasquirt route.

As a side note related to the LS3, I have heard that people have bad reliability problems with the aluminum LS3 blocks when pushing more than about 750hp, as they aren't quite as rigid as the iron blocks.

 

[Jeff W]

RE: LS 3-750, good to know for someone else, but I don't want to come close to that.

I checked out that Megasquirt site...that landing page is awful and unreadable, and the product descriptions are full of spelling, broken links, and other errors. As far as the traction features, I didn't see anything other than launch features that limit spark/rev, or if something like this is EPA compliant. Not trying to disqualify what you're saying, but the Megasquirt is a poor example if it's supposed to represent actual traction control that limits individual wheel slip on launch and acceleration. Other aftermarket ECUs seem to indicate they won't work to pass inspection, but I'm sure there are workarounds. I live in NY, so I'm sure they require whatever standard smog equipment for the year engine I get.

Traction control requires a lot of features that the SL-C doesn't have like wheel sensors and ABS systems, has anyone had success installing it in cars like this?