C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Building a sub-5s 0-60 L98

 
Old 04-12-2019, 04:27 PM
  #101  
confab
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Holy Hell.. 400 HP pickup trucks!
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Old 04-12-2019, 04:35 PM
  #102  
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You could get (option) a 400hp 1500, 10 years ago from GM.
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Old 04-12-2019, 04:38 PM
  #103  
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Not with the manners this one has, I bet. The engine management is so complex, they're injecting fuel directly into a cavity in the top of the piston. It can change its valve timing too. Three fuel modes.


Just amazing.

They're going to build things only a computer can operate under full throttle on the highway.
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Old 04-12-2019, 04:41 PM
  #104  
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IDK...probably not, but it was good enough to be available in a Cadillac (Escalade), so it likely wasn't too rowdy.
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Old 04-12-2019, 04:45 PM
  #105  
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Won't be long before the LS1 crowd are just running old junk!
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Old 04-12-2019, 04:53 PM
  #106  
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Think we are there, 350hp is pretty ho hum today.
Wanting to do a 6l for my 02 1500.
Simple ported stock heads, intake and an LS3 cam out to make it super fun and pass smog with oem reliability & just as quiet/smooth as it is now.

Many scoff at truck intakes but they make the tq on the steet, takes hood clearance though.

Last edited by cuisinartvette; 04-12-2019 at 04:54 PM.
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Old 04-12-2019, 06:08 PM
  #107  
84 4+3
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Originally Posted by confab View Post
Not with the manners this one has, I bet. The engine management is so complex, they're injecting fuel directly into a cavity in the top of the piston. It can change its valve timing too. Three fuel modes.


Just amazing.

They're going to build things only a computer can operate under full throttle on the highway.
I've driven a couple trailblazer SS's with the 400 hp 6.0... actually drives better than the escalade with the 6.2... the throttle response (lack there of actually) and shift programming stock makes you think they programmed it because they're afraid the 8 speed is going to spill its guts. The escalade when you nail it goes pretty alright though. Mpg is the same between the two but the 6.2 has afm and deeper gears vs the 4.10s in the ss.
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Old 04-13-2019, 01:34 AM
  #108  
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Originally Posted by Tom400CFI View Post
And BEHOLD, 507HP. Scroll down to the pic of the black pick up truck.
And that engine is $9000 .... not including the computer or the headers they tested it with .... add another $5000 (or more) to get it into a streetable C4.

Last edited by auburn2; 04-13-2019 at 01:43 AM.
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Old 04-13-2019, 10:12 AM
  #109  
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Originally Posted by 84 4+3 View Post
. the throttle response (lack there of actually) and shift programming stock makes you think they programmed it because they're afraid the 8 speed is going to spill its guts....
That is exactly what they're doing with the new transmissions.. They aren't designed for full power shifts. There's a delay under certain conditions to cushion the drivetrain also.

Fantastic design, but it won't behave like the cars we're all used to.

And I sooooo want the newer transmission in my car.. I have a 90 laying on the floor downstairs, just for that. It's too much modding though, and part and parcel of it all is the wire throttle experience you describe.


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Old 04-13-2019, 10:37 AM
  #110  
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Torque Management is found in automatic transmission equiped models. In the past it retarded timing during the the shift, for less than 1 second. The idea is to improve transmission life and reduce failures, by reducing engine output during shift when slippage naturally occurs. Torque Management tends to be one of things turned off by tuners.
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Old 04-13-2019, 10:40 AM
  #111  
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That may end up having a really adverse effect on the transmission and driveline in some models, as they are engineered with torque management in mind.
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Old 04-13-2019, 03:35 PM
  #112  
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Originally Posted by auburn2 View Post
On an engine dyno, or inside an excalade, yes it is easy and cheap to make 450hp. Inside a streetable C4 corvette, it is a heck of a lot more than just "cam, springs, tune", it is also transmission adapter, torque converter (or worse if running a manual), alternator integration, power steering integration, frame modifications, computer, custom wiring harness, custom intake plumbing, MAF, custom exhaust ..... All that stuff costs money. All that costs money even if you use junk yard parts and do the work yourself, and that is really the minimal to be considered "streetable" and still doesn't include things like ac and making the instrument panel work.

A used LQ9 with under 70k miles and with accessories is going to cost $3500 or more. It is possible to find them for less than that but not easy unless you want an engine with over 150k miles. A low mile 5.3 is cheaper, but those are not going to make 450hp with just a cam swap. A new cam, new springs and an off the shelf tune will cost about $600 if you reuse the old lifters and pushrods. Get a dyno tune and do the cam swap right and you are well over $1000 in additional cost before you even start putting it in the car (which is where the real costs are). Super Chevy did a "budget" 460hp 6.0L build back in 2016. Their total cost all in was $5k, they used a carburetor to keep costs low and it did not include any accessories or integration you will need to get it running in a Vette

I am an LS fan and like I said if you are looking for over 600hp it starts to look attractive and economical. 450hp, not really, not really even close.
Don't even know where to start with this garbage. Ah, I won't.
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Old 04-13-2019, 04:52 PM
  #113  
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Is there such a thing as a low mi truck or SUV these days? Havent seen new 5.3 GM crates for sale in awhile (havent looked super hard either)
GM used to sell an HO for pretty fair $. 290hp is nothing to get excited about and youre limited to valve size with the puny bore they have.
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Old 04-13-2019, 11:22 PM
  #114  
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Originally Posted by Krusty84 View Post
Don't even know where to start with this garbage. Ah, I won't.
Garbage? I am using real information which is published and available online and prices which are widely available. I am not just making things up.

Like I said super Chevy did a budget 460hp 6.0 LS build for $5k and it was just an engine, nothing else. They could have cut some corners and done it cheaper sure, but not a lot cheaper and that motor was a long, long way from powering a streetable C4.

Give me a parts list that will get me a 450hp LS motor into a working streetable C4 for $5k. It is just parts and math, if it really is doable it should be easy to prove it out. Heck if it really is as easy as you say I will do it myself.

Last edited by auburn2; 04-13-2019 at 11:36 PM.
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Old 04-13-2019, 11:53 PM
  #115  
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Originally Posted by cuisinartvette View Post
Is there such a thing as a low mi truck or SUV these days? Havent seen new 5.3 GM crates for sale in awhile (havent looked super hard either)
GM used to sell an HO for pretty fair $. 290hp is nothing to get excited about and youre limited to valve size with the puny bore they have.
It is hard to find a low-mile used engine, especially the early 5.3s. Chevrolet performance does still sell the 5.3 engines as crate long blocks though.

12632260
19301946

Last edited by auburn2; 04-13-2019 at 11:59 PM.
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Old 04-14-2019, 03:45 PM
  #116  
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Originally Posted by fredk View Post
I often wonder with the original post how many of these people actually follow through ??

very small percentage...
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Old 04-14-2019, 11:19 PM
  #117  
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Originally Posted by auburn2 View Post
Garbage? I am using real information which is published and available online and prices which are widely available. I am not just making things up.

Like I said super Chevy did a budget 460hp 6.0 LS build for $5k and it was just an engine, nothing else. They could have cut some corners and done it cheaper sure, but not a lot cheaper and that motor was a long, long way from powering a streetable C4.

Give me a parts list that will get me a 450hp LS motor into a working streetable C4 for $5k. It is just parts and math, if it really is doable it should be easy to prove it out. Heck if it really is as easy as you say I will do it myself.
When you are pricing everything new or on ebay, use the word "streetable" (as if it has universal meaning to every gear head) over and over again and start setting parameters like a 70k or less mile 12+ year old long block to fit your narrative... YES, you are posting garbage.

Maybe a part of the our disagreement comes from the love of Corvettes. For me, I don't love Corvettes and I am not a "Corvette Guy". I simply like sleeper cars and C4s make great ones because the early ones are cheap and slow. I understand that a lot of you guys simply wouldn't be willing to cobble together an LS swap for your car because you take a lot of pride in your C4. I don't, hence the name Krusty84, it is fairly a junky car that makes a ton of power and is completely "streetable" by the way.

Last edited by Krusty84; 04-14-2019 at 11:20 PM.
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Old 04-15-2019, 01:05 AM
  #118  
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Well, I've received some great information, and it has certainly driven me to research more. I have learned that the redesign of the next-gen SBC and especially the LS/Gen V blocks and heads give it some advantages you can't easily or cheaply get in a standard Gen II SBC like the L98. The big difference seems to be in the heads; the 23-degree valve angle for Gen II SBC heads seems to be the limiting factor for flow at reasonable lift with a streetable cam, and the larger cams and shorter overall valve train mass on the LS also help run without valve float above 6K RPM more easily. With an L98-based SBC I can see that it's straightforward to make 300 HP, and requires a cam and heads to get above 350 HP, and a stroked bottom end to get above 400 HP but then street drivability starts to become iffy. That is making me rethink my short- and long-term strategy with the car.

My '91 roadster is old and new to me... I was the original buyer back in early '92, sold it in '04, just bought it back a couple of weeks ago. Yes, it was an emotional decision, but aren't all Corvette buys emotional? The 2nd owner dumped a bunch of money into the car, and I'm trying to determine what he spent it on. I know he's changed the cam out, has put 1.6 rollers on it (and changed the valve covers to accommodate them), has done the easy perf mods (intake air grill cutout, EGR removal, no coolant to the TB, air pump removed, plus 1.75" long tube headers and Corsa exhaust, but he's done other things to the engine that I'm still trying to determine. I don't know if the heads are original; they're aluminum but I don't see any 'GM' or typical patterns or marks on the ends or sides of the heads; the ends are smooth except for the drilled and tapped bracket holes. There is a 'W' on the left head, on the top front, on the intake side just in front of the valve cover. The engine is spotless; I don't know if he pulled it, but the engine compartment looks brand-new... the steering shaft, etc.... no dirt or oil whatsoever, like it just left the showroom. The intake, runners, and plenum have no corrosion... they're spotless. I'm sure he pulled the top of the engine off to change the cam, don't know if he pulled the engine out. Don't know if he ported the intake system. There seems to be a short box added between the oil filter with two hoses, one that runs to the oil pan... not sure what that is all about. In short, I know the engine isn't stock, but I don't know what it is. I'm going to get it on a lift on Tuesday, and have a look. I have no idea how to casually determine these things; because I bought the car through a high end exotic car consignment shop I don't have contact info... I'm trying to get it. If anyone has any ideas after looking at some of the photos I posted earlier as to whether the heads are original or if they see anything else, I'd welcome them.

Without disassembling the engine I have no idea how to determine exactly what's been done to it... I'm assuming it's the original bottom end, but I was also told that the 2nd owner put $25K into the vehicle above the original purchase from me. I can see he spent $10K on a beautifully-done high-end paint job to the original color (have the invoice), plus new C5 ZR1 wheels and C5 brakes front and rear complete with vented rotors, and repairing the Bose audio system, but where'd the other $15K go? Once I determine what I have, then my short-term decision will be based on dyno-ing it. Assuming it's the L98 block, pistons, and heads, with just a cam, my long-term strategy is either going to be rebuild into a 383 stroker with Fast Burn heads and a FIRST TPI intake system with a mild Lingenfelter-spec 219 or thereabouts cam... or I'll look into having a 400 built on a Bill Mitchell Motown LS block, with LS intake and heads. I think the 383 on the current block would get me into the mid-4 second 0-60 range, for $6K - $8K, and the 400 BM/LS would bring it to below 4 seconds but for $10-$12K. I'm likely going to drive it for a year before I decide, given that I think most of what can be done to an L98 without rebuilding it has been done.

Last edited by obijohnkenobe; 04-15-2019 at 01:08 AM.
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Old 04-15-2019, 09:10 AM
  #119  
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Originally Posted by obijohnkenobe View Post
The 2nd owner dumped a bunch of money into the car, and I'm trying to determine what he spent it on. I bought the car through a high end exotic car consignment shop I don't have contact info... I'm trying to get it..
Have you gone back/called the dealership to try and get the previous owners contact information?Shouldnt be that hard to track him down to actually see what was done I also think the biggest restriction on your car car are the runners and manifold/throttle body but you should still port the heads(if not already done) and with some 3.73s and a new dynotune you may be very happy with the performance of the car and it will still look stock

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Old 04-17-2019, 01:18 AM
  #120  
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Originally Posted by obijohnkenobe View Post
"The big difference seems to be in the heads; the 23-degree valve angle for Gen II SBC heads seems to be the limiting factor for flow at reasonable lift with a streetable cam, and the larger cams and shorter overall valve train mass on the LS also help run without valve float above 6K RPM more easily."
Yep, that is the big limiting factor of the SBC stuff. It took me over a decade to figure that out. 15>23 in the flow world.

Anyone have the build list for the Fasterproms C4 BTW? That thing is a beast and would most certainly outrun any type of N/A LS build I have been talking about.
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