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So, someone help me here. I can't see how a 383 with decent heads and an intake that will flow 300 cfm will be any less powerful than an LS that is swapped in, or even a new LT1. The new LT1 is about the same displacement (378 ci). What is the magic that I can't get with a stroker 383?
The magic is you have A LOT more room to make a lot more power in an LS or LT compared to a STREETABLE small block Long RUNNERED TPI 460hp N/A in that setup is hitting its upper limits 460hp in an LT1 is of course just getting started BUT I think it’s a perfect setup for what the OP wants as he’s not looking for maximum hp he’s looking just to run with the newer models and wants factory looks 460hp and 500+ft lbs is plenty fast and fun in a street car IMO and should make a manual C4 outrun a stock manual LS3 and Stingray
The "Magic" is actually this: Ten times the tq got their HP using the GROSS method. GM got their HP using the NET method. You can chop 50-70 hp right off the 10xthe tq article, when you put it in the car. GM's number is AS INSTALLED.
The "Magic" is actually this: Ten times the tq got their HP using the GROSS method. GM got their HP using the NET method. You can chop 50-70 hp right off the 10xthe tq article, when you put it in the car. GM's number is AS INSTALLED.
Er, since the early 1970s GM has been listing engine HP and torque using SAE Net... but that is at the flywheel. The difference between SAE Gross (the earlier way) and SAE Net is that 'Net' requires the engine to be as-configured in the car (all accessories, as-shipped intake and exhaust systems). So, today's LT1 HP and torque figures are on an engine dynanometer (not a chassis dynanometer) and ignore driveline losses. I think the 'Ten Times' article is effectively doing SAE Net testing, as they are testing at the flywheel using the as-configured intake and exhaust systems (variations of TPI and headers)... apples to apples. I'm pretty sure that a '19 Stingray will not be producing 460 HP on a chassis dynanometer... likely in the mid to high 300 HP range.
Er, since the early 1970s GM has been listing engine HP and torque using SAE Net... but that is at the flywheel. The difference between SAE Gross (the earlier way) and SAE Net is that 'Net' requires the engine to be as-configured in the car (all accessories, as-shipped intake and exhaust systems). So, today's LT1 HP and torque figures are on an engine dynanometer (not a chassis dynanometer) and ignore driveline losses. I think the 'Ten Times' article is effectively doing SAE Net testing, as they are testing at the flywheel using the as-configured intake and exhaust systems (variations of TPI and headers)... apples to apples. I'm pretty sure that a '19 Stingray will not be producing 460 HP on a chassis dynanometer... likely in the mid to high 300 HP range.
I think you misunderstood Tom, he was not referencing chassis dyno numbers he is referencing gross vs net HP as rated by the factory before 1971 and after 1972. The way dyno operators show there HP is essentially gross HP rating as before 1971. The factory shows their numbers as net just like the engine is installed in the car with, all intake, exhaust, and accessories operating which provides a real world expected outcome. All Tom was mentioning is that 10 times the torque is comparing dyno numbers arrived at in a gross rating to each other. if you compare 10 times the torque gross numbers to factory net numbers you need to reduce account for that difference which will either lower the gross numbers or change the net numbers for the new engine to gross numbers. A current 460 HP net factory HP rating will be close to 505 HP gross rating on an engine dyno at a speed shop.
So, someone help me here. I can't see how a 383 with decent heads and an intake that will flow 300 cfm will be any less powerful than an LS that is swapped in, or even a new LT1. The new LT1 is about the same displacement (378 ci). What is the magic that I can't get with a stroker 383? Especially when I read in the 'Ten Times' article that is found elsewhere on this site that you can get nearly the power out of a stroked L98 with some work on the factory intake and a mild cam.
Er, since the early 1970s GM has been listing engine HP and torque using SAE Net... but that is at the flywheel. The difference between SAE Gross (the earlier way) and SAE Net is that 'Net' requires the engine to be as-configured in the car (all accessories, as-shipped intake and exhaust systems). So, today's LT1 HP and torque figures are on an engine dynanometer (not a chassis dynanometer) and ignore driveline losses. I think the 'Ten Times' article is effectively doing SAE Net testing, as they are testing at the flywheel using the as-configured intake and exhaust systems (variations of TPI and headers)... apples to apples. I'm pretty sure that a '19 Stingray will not be producing 460 HP on a chassis dynanometer... likely in the mid to high 300 HP range.
Hang a Gen V LT1 on the engine dyno the same way as that 383 (optimal exhaust, electric water pump, no accessories) and it will produce 500+ hp and 500+ tq easy.
I think the 'Ten Times' article is effectively doing SAE Net testing, as they are testing at the flywheel using the as-configured intake and exhaust systems (variations of TPI and headers)
Here is where you've gone awry. You can see in the pics from the 10x the TQ article that they're not measuring "Net".
1. How could the magazine editors possibly do it "as installed"? What vehicle is their test mule going into? They don't know.
2. No water pump
3. No air filter or intake ducting of any kind
4. No smog pump
5. No cats
6. No exhaust
7, No alternator
8. No AC
9. Optimized tune
10. cold water temps
11. cold inlet air temps
They way that they're testing the 10x the tq engine is how GROSS numbers are generated. Those numbers are GROSS...not net. Chop off ~50-70hp from the magazine article #'s and you'll be in the ball park.
Here is where you've gone awry. You can see in the pics from the 10x the TQ article that they're not measuring "Net".
1. How could the magazine editors possibly do it "as installed"? What vehicle is their test mule going into? They don't know.
2. No water pump
3. No air filter or intake ducting of any kind
4. No smog pump
5. No cats
6. No exhaust
7, No alternator
8. No AC
9. Optimized tune
10. cold water temps
11. cold inlet air temps
They way that they're testing the 10x the tq engine is how GROSS numbers are generated. Those numbers are GROSS...not net. Chop off ~50-70hp from the magazine article #'s and you'll be in the ball park.
.
Tom is right.
Here is an article with GROSS numbers for the Gen V LT1 https://www.hotrod.com/articles/518-...traight-crate/ , it made 518 hp and 520 tq.
I suspect that the GROSS numbers of my little cammed 6.0 w/ LS3 heads would be in the ~500-520 hp and ~490-510 tq range.
x2 That article is complete bs and extremetly misleading .Will it run hard on the street sure but lets be real. 530, 540 lbs of torque are stout 400-500 ci numbers.
More than one member over the years has copied that recipe, dynoed then wondered whats wrong with their car?
Okay, I stand corrected. If I look at the 'Ten Times' article, it shows a base L98, albeit with an aftermarket cam, putting out just over 300 HP, and the L98 with honed TPI putting out 450 HP. Is it safe to say that I should expect to see 150 HP increase with a stroked 383, less 15% to 20% for powertrain losses? That would put the 383 L98 in a car at around 360 to 380 RWHP... right?
Is the intake the major difference here? I can't see how two similar engines (similar bore and stroke) can be so far apart HP/TQ wise.
I think the next step would be to dyno the car to get a baseline.
Last edited by obijohnkenobe; 04-11-2019 at 06:41 PM.
Extrude honing and stroke wont pick up that much power. It will definitely be noticeable though.
Baseline is always good to see what you did helped, did nothing or hurt it. Or a timeslip
'Ten Times' article, it shows a base L98, albeit with an aftermarket cam, putting out just over 300 HP, and the L98 with honed TPI putting out 450 HP. Is it safe to say that I should expect to see 150 HP increase with a stroked 383, less 15% to 20% for powertrain losses? That would put the 383 L98 in a car at around 360 to 380 RWHP... right?
I'm not sure where in the article you saw 300 hp for a 350 TPI w/a cam. I saw the engine...but only that it "had problems" forcing them to move on the the 383 with a MUCH larger cam.
I don't think your math is realistic. First, the "300" number is:
1. A GROSS hp number, and
2. it's got a cam to boot.
So assuming you'll get "+150 hp over 300 with a stroked 383"...and that = 450hp....is off.
Your REAL starting point is 245hp. +150 = 395 hp -15% drive train loss = ~335 @ the wheel or so. -Note that this number is ~120 WHP over stock TPI WHP results.
So will you gain 150 hp with a stroker? Maybe....IF you also add TFS heads or comparable, a stout cam, and other details. If you're retaining the stock 113 head, then I'd say NFW on any "+150hp".
I definitely agree w/getting a baseline...both RWHP and Drag track.
$5k and making everything work like stock probably isn't going to happen for many folks. However, for $5k I think it is doable to get the swap done, make the car run and drive and go outrun C6s and C7s on the street.
I know some of you guys have much higher standards on what you would personally run in your C4s but to totally discount the frugality and capability of used/junkyard parts is a little insincere in these arguments. The $2500 on the short block you are talking about could literally complete then entire engine leaving the other $2500 to get it in the car.
Getting a 6.0L LS engine to 450chp is extremely easy. Like cam/springs/tune easy.
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.
Probably the fastest C4 on this forum is running a SBC!!
That aside, everyone seems to forget, parts for the SBC and LT1 have become much better over the past few years vs what was out there 20 years ago. For example, a set of AFR 210 heads that flow 300 cfm out of the box... That was unheard of 20 years ago.
Funny thing is, in reality, there are very few of these LS converted C4 on here, and even fewer showing track times......
So how about some timeslips posted, mods required, what it cost, and convince the rest of us its worth it!!!
So, someone help me here. I can't see how a 383 with decent heads and an intake that will flow 300 cfm will be any less powerful than an LS that is swapped in, or even a new LT1. The new LT1 is about the same displacement (378 ci). What is the magic that I can't get with a stroker 383? Especially when I read in the 'Ten Times' article that is found elsewhere on this site that you can get nearly the power out of a stroked L98 with some work on the factory intake and a mild cam.
One difference between gen1/2 and gen3/4/5 sbc is that the cam diameter increased from 47.5 mm to 55 mm. That means more control over the valve per revolution. I don't know the specifics, but there's something about decreased valve acceleration with aggressive profiles.
Hang a Gen V LT1 on the engine dyno the same way as that 383 (optimal exhaust, electric water pump, no accessories) and it will produce 500+ hp and 500+ tq easy.
And BEHOLD, 507HP. Scroll down to the pic of the black pick up truck. Read the text right above that pic. Good call Krusty.
04-11-2019, 07:56 AM
Probably the fastest C4 on this forum is running a SBC!!