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HPR and GSpeed team up on a 468 cid road race setup
-Build Thread-
HPR and GSpeed have teamed up to showcase a number of new cool and exciting engine and power-train offerings for late model Corvette's, particularly for road racers. In this continuing build thread you will see maybe some things you haven't thought of before, but all are either currently available or so to be available products you can have for your own racer or street car. There has been a common urban myth surrounding the world of road racing, and that has been to have a higher reving engine you need a shorter stroke. You can find this from the history pages of the Chevy 302 back in the early TransAm days of racing right up to the new destroked LS7 builds that have been growing in popularity. Some of these engines were due to rule limitations like the TransAm series but others were done just because that is what was thought to be the only way to do it. What did it really prove? It takes a lot more RPM to make the same amount of HP from a smaller engine, and low to mid range torque suffers because of it. Since most of us on here are not racing in a class that has a displacement rule, why handicap yourself right out of the gate by using a smaller engine? I know the love affair with a 8500 RPM V8 is one that we all love to hear blasting down the straights but what if I told you you can make so much power across the board there is no point in doing so? What if I also said, if you need to spin it that high and can feed it....there is no reason a big stroke LS engine can't spin to 8000 RPM or more? :D (more on that later). Goals: To build a reliable and cost effective LS performance engine package without using exotic or high maintenance components. Highlights: New and innovative products Outline:
Episode 1 Short block. In our talks with Louis the goal on this first engine was to make a big powered engine obtainable to most weekend racers or street cars. No high dollar shaft mount rocker arms. No solid roller cams that would need constant adjustment. No limited production billet cranks or high dollar connecting rods. The best starting point, our signature 468 cid LS of course. Ground zero is the engine block itself. We use a Darton dry sleeved Gen IV LS engine block as our starting point. In this case it is the typical 5.3L casting. Inside we do use a longer than stock sleeve to better support the increased stroke of the 468. Stock GM main caps are supported with ARP studs and hardware. https://cimg5.ibsrv.net/gimg/www.cor...9dcf4c6c9c.jpg Sleeved block From here we clearance the block to clear our connecting rods for the increased stroke with minimal intrusion into the liners. New cam bearings are installed, main caps are torqued and line honed for proper clearance for the mains. Cylinders are honed to our finish requirements and the deck surface milled to spec. Once machine work is finished, the engine is washed and ready for assembly. https://cimg1.ibsrv.net/gimg/www.cor...35a3b9ff08.jpg Checking Mains The forged crankshaft is measured for journal sizes and prepped for balancing after weighting all components used. https://cimg8.ibsrv.net/gimg/www.cor...1a81a7d849.jpg Balancing the crankshaft Pistons and rods are honed for proper pin clearance then deburred and washed. The 468 uses a number of components of our own Erik Koenig's design like the pistons and ring package for not only a good seal but reduced drag and friction which again aids in horsepower! Here you can see the rings being sized for gap prior to going on the pistons. https://cimg1.ibsrv.net/gimg/www.cor...eed4d6dac9.jpg Checking rings Once the rods are washed, bolts are lubed and bearings installed prior to hanging the pistons. Another one of Erik's designs was a strong, yet light rod that provided more clearance for the large stroke on our 468. https://cimg2.ibsrv.net/gimg/www.cor...0a236da368.jpg Connecting rod detail With the rotating assembly balanced, parts fitted and washed it is time to assemble. https://cimg3.ibsrv.net/gimg/www.cor...d1fd97b7b2.jpg Caps going on First step is installing bearings into the block and laying the crank in place. Here we can check final rotating drag and trust movement before installing the piston/rod combo. https://cimg4.ibsrv.net/gimg/www.cor...bdccf02fa0.jpg Pistons going in Correctly sized ARP ring compressors are used to install each assembly into the engine block using Motul break in oil. https://cimg5.ibsrv.net/gimg/www.cor...b992ad7da2.jpg assembled short block Once the short block has been assembled we can go in and check our work for deck height at each corner and prepare to install the cam and timing sets coming up in the next installment! Sneak Peak - This is one of the brand new items that you will also see featured on this engine build. Louis and the team at GSpeed have developed a completely new front accessory drive for the Corvette. In short, this system has removed 30 lbs of weight off the nose of the car, which is always a big plus. What else is this going to do? It is going to give you a better water pump for increased cooling. A real road race power steering pump setup. Smaller and lighter pulley system, and narrowed belts for less frictional drag. In end not only will it remove weight but you are going to see increased RWHP and quicker acceleration. I'll let GSpeed go into more details on this one. https://cimg7.ibsrv.net/gimg/www.cor...cba0a63160.jpg C5/6 Corvette accessory drive system from GSpeed STAY TUNED! |
First comment in, and for that privilege I only need to say this:
Holy sh*tballs, this is exciting |
:bigears :bigears
I like where this is going! |
:lurk: sounds awesome!
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Sounds good
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Curious how you deal with the piston slap issues and the shorter sleeve for the 442 I see on your website, that's a heck of a long stroke. I'm sure it's a custom piston but would be interested in a bit more detail. Do you still recommend that motor as a road race motor?
Also, what are your thoughts on piston velocity in a road race LS? All the info I find on it seems incredibly outdated and based on a flat tappet SBC with cast rods versus modern motors or ones using forged materials. |
Originally Posted by synner
(Post 1595620919)
Curious how you deal with the piston slap issues and the shorter sleeve for the 442 I see on your website, that's a heck of a long stroke. I'm sure it's a custom piston but would be interested in a bit more detail. Do you still recommend that motor as a road race motor?
Also, what are your thoughts on piston velocity in a road race LS? All the info I find on it seems incredibly outdated and based on a flat tappet SBC with cast rods versus modern motors or ones using forged materials. Both the 442 and 468 would be fine to use a street engines, drag, or road race. Now because of the short skirt design we do not suggest them on power adder cars, so they should be left as NA only builds. There is no reason why either one of these engines couldn't turn 10,000 RPM as far as the short block is concerned. Piston speeds at that RPM are not even close to what is done in current Pro-Stock drag racing...which you might say...that isn't road racing...but the engine doesn't care (at least as far as RPM goes). What is going to be a concern...or I should say the work is going to be, is feeding an engine of that size to turn those kinds of RPM's. A lot of flow in the heads is going to be needed, a very stable valve train, and intake system to feed it all. The small engines, like the de-stroked LS7, are shall we say easier to do. The engine is smaller and most ported LS7 heads can support the air flow requirements at 8000, 8500 RPM and not really fall of on power production. If anything they probably actually like it there given the smaller size of the engine. On a side note, if you want a 10k RPM engine, going to have to go aftermarket on the sensors and ECU to run it too...but that is a separate topic. Stay tuned..this first engine you see here will be a milder system build (still over 7200 RPM) that I think most will probably opt to do. We will be featuring a high RPM one as well down the road. Can't show you everything :thumbs: |
Would love to see/hear some vids of these beasts. Wish the guy that won the optima qualifier had a good vid of his car, I couldn't find nuttin. 468 gotta sound monstrous through the right pipe setup.
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In for details. Definitely interested in the accessory drive!
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Moving forward.
In sticking with our target of building a reliable big displacement road race engine while using currently available shelf parts without going to crazy on our budget. We are sticking with a hydraulic roller camshaft and OE rocker arms and using current on the market head. A lot of thought and planning had to be done when it came to the camshaft design. Unlike a drag engine that sees only seconds at WOT, this engine is going to see up to 40 mins at a time on track. Louis at GSpeed, Mr. Godbold at Comp Cams, and ourselves spent a good amount of time working together on choosing the correct pieces to fit within our design and budget layout. More on this later. First off the easy stuff. Lifters. In keeping with a 'shelf' part and affordable hyd. roller build we are choosing to use the GM COPO spec lifters made by Johnson. These are the same ones you will find in the 8000RPM factory COPO drag cars and retain the OEM lifter buckets and stock lifter dimensions. Erik has used and tested these in the past, and when used with the proper supporting hardware, prove to be a very solid lifter design. Some of the highlights of these lifters include:
https://cimg5.ibsrv.net/gimg/www.cor...89279f894a.jpg COPO lifters oiled and ready for install Cylinder heads GSpeed and ourselves when over a number of head designs and options out there from LS3 to LS7 style versions. For the purpose of having a solid power band through as much of the RPM range as we could, we settled in on a set of Mamo Motorsports reworked Trick Flow 260 LS7 head. Louis at GSpeed spec'd these out with a lightweight 73 gram Titanium intake valve and equally light 85 gram stainless exhaust valve. Tony Mamo did his thing on the ports and chambers for what should be a very well flowing cylinder head (flow numbers not available at time of this writing - updated when I have them). https://cimg2.ibsrv.net/gimg/www.cor...a974241b3b.jpg MMS 265 LS7 reworked TF260's https://cimg7.ibsrv.net/gimg/www.cor...dd9ef66f16.jpg Trick Flow 260 LS7 casting https://cimg0.ibsrv.net/gimg/www.cor...fc184e68eb.jpg Tear down for measurements https://cimg4.ibsrv.net/gimg/www.cor...0a31ae05cb.jpg chamber with valves installed https://cimg7.ibsrv.net/gimg/www.cor...291547def4.jpg chamber with valves removed https://cimg9.ibsrv.net/gimg/www.cor...f5ede6ef8d.jpg intake port Now the camshaft. Mr. Billy Godbold, the mad scientist at Comp Cams, is probably the leading authority when it comes to actual cam designs and testing valve train systems. Because we are working with an engine designed for lengthy run times on track. A very soft and stable ramp profile of Billy's was chosen along with a new finish of his own working as well on the camshaft. Just shown for the first time at SEMA this year, you will be seeing this much more in the future from Comp Cams. "We changed our grinding wheels and dress parameters to maximize the load distribution and then wanted a light treatment just to take the fuzz off the top of the topography (like running a finishing mower across a baseball or soccer field). Many of the treatments left a dull finish, but the best one we tested included the burnishing fluid and denser media that also resulted in that more mirror like look. I just don’t want anyone to think it was supposed to be so good looking, but the best finish we developed just had that as a side effect." - Billy Godbold https://cimg4.ibsrv.net/gimg/www.cor...ab5744dfa5.jpg COPO lifters, GM lifter trays, 4 pole cam gear, C5R timing chain, Comp Cam, and hardware https://cimg5.ibsrv.net/gimg/www.cor...207d55b405.jpg Close up of the new finish on the cam https://cimg7.ibsrv.net/gimg/www.cor...79bda58317.jpg Sliding the cam into the 468 lubed with plenty of Motul break in oil NOTE: Like any doctor we do respect the privacy of our customers so the actual cam specs are not disclosed publicly or to other customers unless GSpeed would like to post them. For valve springs and rocker arms. Using Billy's own data along with specs from the rest of the build we decided to use a new Comp single spring the 7230 conical. Billy has been using these in his own enduro LS running 8-12 hr races without issue. These will be finished off with a Tool Steel retainer for life, and since they are so small, there is no weight penalty compared to a larger dual spring Ti retainer. https://cimg3.ibsrv.net/gimg/www.cor...a08ecda7ac.jpg Comp 7230 spring and Tool Steel Retainer https://cimg4.ibsrv.net/gimg/www.cor...ac43c6ae19.jpg The master himself, our own Erik Koenig checking cam timing. Stay tuned as we finish out assembly and completion of the long block coming up!!! |
Small update for today:
If you are curious as to the retainer weight difference here is the original PAC Ti retainer for the dual spring compared to the Tool Steel one for the conical Comp springs. https://cimg3.ibsrv.net/gimg/www.cor...4c4f5eb1dd.jpg Pac Ti. retainer at 11 grams ea https://cimg0.ibsrv.net/gimg/www.cor...ba9c520370.jpg Comp Tool Steel retainer for conical springs For desired compression and quench we are using a 0.051 Cometic gasket set. Heads are held down with a shelf ARP head bolt kit. https://cimg5.ibsrv.net/gimg/www.cor...4eb999421b.jpg With the gaskets on, heads were checked for correct install height, shimmed as required and prepared to go on the engine. https://cimg2.ibsrv.net/gimg/www.cor...9ca3ee76fe.jpg As sent dual springs with Pac retainers being removed and the heads cleaned. https://cimg4.ibsrv.net/gimg/www.cor...883995aea8.jpg Shimming for new Comp conical spring kit https://cimg6.ibsrv.net/gimg/www.cor...0db14a03be.jpg Comp's 7230 conical spring set with tool steel retainers ready to go. https://cimg7.ibsrv.net/gimg/www.cor...17a4146aa2.jpg Heads assembled and torqued Now that the heads are on, we measured for proper pushrod length and lifter pre-load. Unlike the home user, we have the advantage of keeping a number of pushrods of different sizes and lengths in stock so we can check using a real pushrod, not a checking pushrod. This gives us the ability to look for clearance issues, or any differences from the checker to a real constructed pushrod. *pushrods in route* https://cimg0.ibsrv.net/gimg/www.cor...ea32a95754.jpg Measuring for pushrod length Now for some of the new cool features. As you have seen in the first post, Louis and the guys at GSpeed are working on a new dry sump and accessory drive system to allow use of a bigger pump than the standard 3 stage as well as dropping weight with the new accessories and picking up some HP to boot. First part of this is the Dailey 5 stage pump with Aerator return. https://cimg8.ibsrv.net/gimg/www.cor...edd5be9a52.jpg Assembled pan and pump https://cimg4.ibsrv.net/gimg/www.cor...51146628c7.jpg Detail work inside the Dailey pan and built in pickup screens https://cimg7.ibsrv.net/gimg/www.cor...1b24d29997.jpg Pump return, and aerator return side by side. https://cimg0.ibsrv.net/gimg/www.cor...b5740b5feb.jpg Mounted on the engine Again, I will forward some of the new drive features to Louis and the guys at GSpeed. I'll answer what I can on this. |
Final pieces before we hand it off to Louis and the crew at GSpeed for their drive assembly, sensors, and wiring harness.
One of the things that Billy Godbold had tested with using the new conical single spring and Comp lobe design was the OE rocker and a new Comp design. Since the Comp rocker is still in development and not ready for sale, we went OE on the rockers. A large part of the goal of this first build is to choose proven components using a sensible budget, and with Billy's spintron testing, there was no worry on the OE rockers. Louis at GSpeed took the time to pull them apart, tumble them, polish and install Comp's trunion upgrade kit before sending them over for install on the engine. New Trick Flow rocker stands locate using two dowels into the cylinder heads. Due to some tight pushrod clearance, we are using a heavy wall 3/8" diameter pushrod for rigidity as our typical 7/16" would not clear in this case. https://cimg1.ibsrv.net/gimg/www.cor...04da41564a.jpg https://cimg7.ibsrv.net/gimg/www.cor...2429e9b971.jpg Tumble polished with Comp trunion upgrade https://cimg8.ibsrv.net/gimg/www.cor...4a72521d81.jpg HPR 3/8" diameter, 0.135 wall pushrods https://cimg9.ibsrv.net/gimg/www.cor...38e5862bfd.jpg Trick Flow billet stands with new LS7 rocker arms https://cimg0.ibsrv.net/gimg/www.cor...3b3fb3a6f2.jpg Comp's conical spring and OE rocker arms https://cimg3.ibsrv.net/gimg/www.cor...de4aa7c248.jpg Finished long block complete with GSpeed exclusive 5 stage Dailey Engineering Dry Sump All bagged and ready for customer pickup for the finishing bits! Stay tuned as GSpeed finishes up the new Motec wiring harness in the coming weeks and we get ready to fire it up! |
Ooooo Wee! Thanks HPR! Cant wait to get it in the car and make some noise. :cheers:
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So I saw in the opening post that the goal was "To build a reliable and cost effective LS performance engine package without using exotic or high maintenance components."
Looks interesting but "cost effective" is variable from one person to the next. Do you have a price point target that you are shooting for? If so, can you give us an idea of what it might be? Thanks |
Originally Posted by fmcokc
(Post 1596311867)
So I saw in the opening post that the goal was "To build a reliable and cost effective LS performance engine package without using exotic or high maintenance components."
Looks interesting but "cost effective" is variable from one person to the next. Do you have a price point target that you are shooting for? If so, can you give us an idea of what it might be? Thanks Taking the 5 stage dry sump system out of the equation, a 468 long block could be done for say $12-13k fully assembled (using your heads as cores) ready for your intake, exhaust, and accessories. Figure another $3500ish for a 3 stage dry sump system. They all vary of course depending on what the customer wants on components inside but figure a rough estimate around that. Its so hard to quote one when doing custom engines as the crankshafts alone can vary $700-3500 in price, rods $500-1800, pistons....just so many variables it's hard to say without knowing 100% what the customer wants. There are various ways to say it but...lets call it doing it more of the optimal way with a fully counter weighted crank, small journal rods, bigger cam core, solid roller, better heads....you would be looking at $35k + for a long block with dry sump. Now is that going to buy you 2x the power for 2x the money? Probably not but it might gain you 2000-2500 RPM (yes it could turn 9k+ so long as you have the computer to run it, and the supporting top end to feed it) and another 100-150 hp so long as you have the intake system to support it. Now on this one in particular I would have to speak with GSpeed as they had already purchased the heads to give you more of a ball park in what this exact combo would be to duplicate. |
where are all the "internet engine build experts" screaming bloody murder seeing beehive springs? lol
sweet build...wish I had the coin to do the same. |
Originally Posted by HP RESEARCH
(Post 1596311973)
Very true, there are a number of budgets to look after and what is cost effective to some may not be to others. For someone looking at a build such as this, I'm assuming they are not expecting a $7k crate engine at this level.
..just so many variables it's hard to say without knowing 100% what the customer wants. Thanks for sharing this really thoughtful and impressive build with us!! Can not wait to see power results and then hopefully see some video of how it performs on the track!! |
We have had a few questions come in about this particular build. The engine is completed at GSpeed but the car in question is going to be doing some class racing for the remainder of the year and the 468 is not legal for that class, so it will possibly be testing over the winter.
We do have a few more variations of the 468 coming up for local customers, and a few more for the group at GSpeed to show off some other combo's as well. |
Really wanted to hear this beast....
Could it be feasible to just do a 468 shortblock, put on LS6 heads/intake/exhaust as a means to get it in the car, tuned/running, then upgrade the top end as budget allows? Certainly would choke it but, I imagine it'd still be stout, no? |
I still want to know about the revised accessory drive system.
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