When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I still want to know about the revised accessory drive system.
I know the guys at GSpeed are off doing a bit of testing at COTA for the big NASA National event coming up in a few weeks. The two biggest items with that front drive are going to be dropping weight and picking up lost power from the accessories. Don't write this in stone but I believe it drops a bit over 20lbs off of the front of the engine and has shown a good gain in power from the TA car they have been testing it with.
I'm curious if the 20 lbs is due to deleting the AC compressor? I can't see any other way to drop that much weight with a revised drive system.
-Scott
Originally Posted by HP RESEARCH
I know the guys at GSpeed are off doing a bit of testing at COTA for the big NASA National event coming up in a few weeks. The two biggest items with that front drive are going to be dropping weight and picking up lost power from the accessories. Don't write this in stone but I believe it drops a bit over 20lbs off of the front of the engine and has shown a good gain in power from the TA car they have been testing it with.
I'm curious if the 20 lbs is due to deleting the AC compressor? I can't see any other way to drop that much weight with a revised drive system.
-Scott
No, as the car had a Dailey on it before so there was no A/C before or after. Different water pump, different alternator, different PS pump, different brackets, different pulleys and everything is way smaller than OE. It all adds up. I'll see if Louis has some time to verify all of that today as that is their project.
2014 NASA Texas TT1 Champion
2015 NASA Texas ST1 Champion
2018 NASA TTU & TT3 National Champions
2019 NASA ST2 National Champion
2019 NASA Texas TT2 Champion
2020 SCCA Majors COTA GT2 pole sitter
2020 SCCA Trans Am Road Atlanta SGT Winner
2022 NASA National Champion ST2
2023 NASA National Champion ST2
2023 NASA National Champion TT2
Anthony is correct. This engine was built for NASA ST, where anything was legal, you just needed to maintain a power to weight ratio for the class you are running in. Since we decided to move this car to another series, it has specific limitations on the engine, and we cannot run the 468. Having said that, depending on how things go, we will install it in the car for a few weekends to see where we stand power wise, and how the car behaves. We like to run at COTA in the winter, and this would be a good time to do that, provided we dont need the testing for the other series. Here are some pics of the car its going in.
testing total clearance. This is where the suspension went into bind, and tire is 1" above the chassis. (Chassis scrapes, tire has plenty of clearance. )
The GSpeed team cut the inner fenders to clear the large tires required in the new series. This is zero ride height.
Wheels on for some real life ride height measurements. this is 4" from chassis to ground.
Holy mechanical marvel Batman! (That really is from the old Batman TV show!). I had no idea there was that much weight savings potential in the accessory/drive system.
Would the water/steering pumps and alternator will have enough output for both track and street duty or is this primarily a racing oriented setup. When do you anticipate availability?
Thanks for the detailed response.
Originally Posted by GSpeed
Hi Scott, heres the break down:
Old parts:
Water pump/tensioner 15 lbs
alternator 15.5
power steering pump/lines/cooler/reservoir 8.9
accessory bracket 4.55
Balancer (OEM) 9
TOTAL 52.95 lbs
New parts
Water pump complete 8lbs
Alternator 6.8lbs
Power steering pump/pulley/lines/cooler/reservoir 5.8 lbs
brackets/ 0.8 lbs
balancer/drives 7.2lbs
TOTAL 28.6lbs
TOTAL Savings = 24.35
This excludes Moment of intertia due to the light weight pullies, and HP gained from spinning everything 50% slower than stock.
Holy mechanical marvel Batman! (That really is from the old Batman TV show!). I had no idea there was that much weight savings potential in the accessory/drive system.
Would the water/steering pumps and alternator will have enough output for both track and street duty or is this primarily a racing oriented setup. When do you anticipate availability?
Thanks for the detailed response.
Were building them on an as needed basis now. Its main goal is racing, as power steering and alternator output are full on by 3000 rpm, but say you wanted to cruise at low rpm, you would not have full power steering (pump spins at 400 rpm at idle, and needs 1500 rpm for total power assist) and alternator is half the size, both weight and amperage, but its also engineered to be full output by 3000 rpm as well.
Cost is high, if its something you think you might be interested in, I can send you the info. Engine must be moved back .750", and to the passenger side roughly .500" to clear everything.
If you don't mind, a couple of questions on the Mamo heads. I am also running a set, so I am curious how these may differ from his typical LS7 program. Any information on additional work that he has done to target the larger-than-normal engine you built? I would expect a lot of people to suggest that the 265cc port of his typical program to be way too small to feed this engine, but I think this will be a great combination based on my own experience.
You mentioned earlier that you could share the flow numbers once they were available. Any chance you can share them now?
You also hinted early in this thread that you may be spinning a lot of rpm with this engine. Where did this one settle out? Was it ever dynoed, and if so, would it be possible to share any data? It's certainly an out-of-the-box combination that I would love to see how it performs! I personally have been very happy with my MMS heads on my 434ci combination, the entire package carries power really well and could easily spin more than I plan to spin rpm-wise.
If you don't mind, a couple of questions on the Mamo heads. I am also running a set, so I am curious how these may differ from his typical LS7 program. Any information on additional work that he has done to target the larger-than-normal engine you built? I would expect a lot of people to suggest that the 265cc port of his typical program to be way too small to feed this engine, but I think this will be a great combination based on my own experience.
You mentioned earlier that you could share the flow numbers once they were available. Any chance you can share them now?
You also hinted early in this thread that you may be spinning a lot of rpm with this engine. Where did this one settle out? Was it ever dynoed, and if so, would it be possible to share any data? It's certainly an out-of-the-box combination that I would love to see how it performs! I personally have been very happy with my MMS heads on my 434ci combination, the entire package carries power really well and could easily spin more than I plan to spin rpm-wise.
Good luck with the testing!
I'll let GSpeed fill in any of the Mamo questions as Louis had spec'd the heads and shipped them over to us. We simply setup the new conical spring for the new lobes from Comp on the cam.
As for RPM I think you are confusing that with the other more race setup engine we are working on for them. The bottom end of the engine (ala the stroke) isn't going to be the limiting factor on RPM so much as the intake setup and valvetrain will be. The MSD intake setup, given the runner size and length of runner, just isn't setup to turn 8,000 RPM and make any kind of power up there. Now there is no reason this engine can not turn 7200 or so on track, but yes the intake and heads will probably keep the PEAK HP around 6000-6200 ish...as you might have seen from 08Z's post using the MSD with one of our 468's.
Again turning more RPM would require more flow from the head on an engine this size as well but the goal is to push power up across the entire band and not have to turn stupid high RPM's with it so the last longer.
As for dyno work, I heard they had the car started last night and were planning on hitting the dyno today with it.
Thanx for the reply. Regarding the RPM target, I was mostly referring to this from the first post:
there is no reason a big stroke LS engine can't spin to 8000 RPM or more? (more on that later).
I wasn't sure what your target for this particular engine was, but I agree that the MSD and valvetrain aren't the right options for max RPM. With a more 'normal' RPM range, perhaps a closer to out-of-the-box Mamo port makes a lot of sense.
Originally Posted by HP RESEARCH
As for dyno work, I heard they had the car started last night and were planning on hitting the dyno today with it.
Can my question from earlier be answered. Can I run the shortblock with LS6 heads/intake, for short term? Is there an issue with head gasket due to bore size vs LS6, or you just match head gasket to bore and you're good? I know it chokes it, but as a stepping stone to getting the entire setup running, buying the short block and massaging my LS6 heads would be best, budget wise. Please advise.
Can my question from earlier be answered. Can I run the shortblock with LS6 heads/intake, for short term? Is there an issue with head gasket due to bore size vs LS6, or you just match head gasket to bore and you're good? I know it chokes it, but as a stepping stone to getting the entire setup running, buying the short block and massaging my LS6 heads would be best, budget wise. Please advise.
The way the 468 piston is designed in our "shelf" assembly, if you will, is designed around 11.2:1 compression using a 70cc LS7 style head. Going to the smaller valve, smaller chamber size of the LS6 (along with a slightly different valve angle) you would have to watch that you do not get to high of compression depending on what your goal is with the engine. You are correct it would be a restriction but given enough info about your heads you should be able to make it work until you wanted to swap top ends on it at a later date.
As for the bore size of the gasket, you just need to make sure the fire ring is not entering the chamber area. In this case, it would need to be larger than the bore of the cylinders, and the head wouldn't matter but in some cases the chamber can actually be what dictates the gasket bore.
Ok, yeah that's what I was assuming to be the case. I think this is my "best method" to get into this motor. I am just looking for a potent 91 octane street/occasional HPDE engine with a broad curve and a lot of grunt, mild cam with reasonable lift, etc....nothing crazy...a longevity motor, something to keep...lol.
I think this puts into perspective just how much more average power the HPR 468 really makes over most stock and H/C/I 427's.
Stock LS7 data pulled from a few posted here online, DynoJet SAE corrected
LS7 H/C/I pulled from a few posted on CF again using DynoJet SAE correction with typical bigger headers, MSD, 102, higher compression.....some have made more, most less.
Which shirt block would you recommend for a St1 c5 Z06 ? Running ls7 heads now on a 434 built by Erik, never got to sample it full power as the shop that did the install plumbed the remote filter backwards and it spun a bearing 10 minutes from the shop. Rebuilt it with lower compression but I think a new short block is needed now.
Which shirt block would you recommend for a St1 c5 Z06 ? Running ls7 heads now on a 434 built by Erik, never got to sample it full power as the shop that did the install plumbed the remote filter backwards and it spun a bearing 10 minutes from the shop. Rebuilt it with lower compression but I think a new short block is needed now.
Ouch, we never like to hear stories of things going wrong like that, especially that quickly into a new build. It is hard to say without seeing what is there and tearing it down if what you have could be used. Never know, it might very well be usable in a new build.
As for that class, just have to look at the rule book to see what would best suit it. For most of the restrictor class setups, a larger engine typically will do way better as it will just make the same torque everywhere, effectively turning it into an electric motor in a way.
08-27-2018, 04:02 PM
(more on that later).
