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Old 04-20-2009, 02:32 PM   #1
turley849
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Smile L98 Build up!

Hey Guys, I have a pacific build in mine. I want to take my stock 1991 corvette 350(l98)TPI (specs 245hp 345fpt) motor. Build it up, I want to get around 400 Ė 430 hp to the ground. Donít want to lose any torque. I donít want any turboís donít want supercharges. I want it to be like stock. From the crank to the intake, I guess what Iím asking is, there anyone on here that knows what it would take for me to do this task? Know exactly what to get and the specs for it. Thanks guys.
Chris.
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Old 04-20-2009, 02:37 PM   #2
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Have no fear....grumpy will be here...

Whats your budget?
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Old 04-20-2009, 02:39 PM   #3
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Smile

My planned budget is 3-4 or what would it take for me to achieve it?
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Old 04-20-2009, 07:02 PM   #4
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Quote:
Originally Posted by turley849 View Post
Build it up, I want to get around 400 Ė 430 hp to the ground. Donít want to lose any torque.
"Build it up "as rebuild as new engine or just bolt parts to existing engine?
Easiest way ; stroke to 383 with big tube / ported TPI or aftermarket intake.
Plenty of torque
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Old 04-20-2009, 07:06 PM   #5
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My l98 is being rebuilt rite now as a 383 stroker. If you find the best machine shop in the area they can prep your block for around $400. I then bought from my machine shop a Probe Industries rolling assembly kit which includes the crank (steel is good for what you want) forged connecting rods and pistons (4340 chromoly steel) rings, and bearings for $1,200. I have Dart heads and a good intake with headers and a cam. I would again find the best machine shop in the area or go a different route and buy a crate 383 motor for around $4,000 complete with heads.

Chevy 383 Flat Top -4.0cc - STREET FIGHTER Engine Kit, 3.750" Stroke

Part Number: 12336-SF-C383
1.425" Compression Height
3.750" Stroke
5.700" Rod Length
Probe SRS Pistons
Cast Steel Crankshaft
Machined Beam (Bushed) Rods
Available Bore Sizes: 4.000", 4.030", 4.040", 4.060"
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Old 04-20-2009, 07:10 PM   #6
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I just noticed your in South Carolina, my car is at my folks house in Myrtle Beach and I am using Jordans Performance machine shop in Conway, SC. 843 248-6845.
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Old 04-20-2009, 08:08 PM   #7
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ok lets go thru this again, to get 425 rear wheel hp you need about 520 flywheel hp
you can,t just slap a few parts on the stock shortblock and expect to get to that power level, and most guys forget the drive train rear gearing,and trans stall,speed, cooling, a low restriction exhaust etc.
it takes (X) amount of fuel/air mix burnt per second to produce (Y) amount of horsepower,you can reach the goal by packing extra fuel/air mix into the cylinders with a supercharger, you can burm MORE fuel per stroke with the extra oxygen in nitrous, you can use a larger displacement engine, you can spin a smaller engine faster or you can make the current engine more efficient with a larger duration cam, more efficient high flow ports and a low restriction exhaust, but the results will be closely linked to the amount of fuel air mix that went thru the engine per second.

youll need decent cylinder heads that flow about 250cfm minimum at .500 lift, ID suggest the air flowresearch 195cc or the brodix 200cc IK as a decent option, trickflow and several other suppliers like dart could also supply a good cylinder head, youll need a cam that opens the valves far enought to get full use of the port flow rate potential and with durration matching the displacement and compression ratio, that will generally be a 383-396-401 stroker combo if you want to use the existing block, the stock TPI intake , CAM,and heads if used together,EVEN PORTED EXTENSIVELY won,t get close to flowing what you need.

heres some reading homework

http://forum.grumpysperformance.com/...php?f=69&t=263

http://forum.grumpysperformance.com/...4&p=3796#p3796
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" IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"
Old 04-21-2009, 05:46 PM   #8
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Grumpy

I just read your article on fuel injectors for your 383. I am confused on what you suggest for injectors. I spke with John at FIC and recommends 30lb injectors for my set up. You recommend 36lb injectors. Here's my set up that's will be going back together in two weeks. What do you think on the size of FIC's injectors and what HP do you think I can expect from this combo.


1987 CORVETTE

Rear End Ratio 3.73

Transmission 700R4 by Select transmission.

Torque Converter TCI-242800 2600 stall speed

662-224-8972 www.tciauto.com

PROM TPIS 410-500 Level 5 prom

952-448-6021 www.tpis.com hpfarm@aol.com

Throttle Body BBK D-245-9 52mm BBK 1583 Gasket

CAMSHAFT ACCEL/DFI SuperRam p/n 74211 Hydraulic Roller

www.mrgasket.com Duration @ .050 211*ex. 219*in. gross lift .525 ex - .533 in

MANIFOLD TPIS p/n 500-509 Big Mouth

952-448-6021 www.tpis.com

PLEMNIUM & RUNNERS ACCEL SuperRam/DPI p/n ACC74196

Eli @ 248-380-2780 www.accel.com

Heads Dart Aluminum p/n 11310010 Pro 1 200cc intake runners

2.02 intake 1.60 exhaust 64cc combustion chambers

383 Rotating Kit Probe Streetfighter p/n 14394 10.26 to 1 compression forged flat top pistons and 6Ē forged rods, cast crankshaft

Ignition MSD 6AL & MSD distributor 915-857-5200

Headers TPIS
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Old 04-21-2009, 07:05 PM   #9
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ok, first let me say a 30-32lb injector is all you currently (NEED) but it won,t hurt a darn thing to have a 36 lb injector as it will give you a good deal more versatility when you upgrade your power in the future , (AND MOST GUYS DO!) so keep in mind the o2 sensor will tell the cpu to shorten or lengthen the injector pulse duration to maintain the correct fuel/air ratio with either size injectors but once an injector reaches about 80%-90% or higher pulse duration it doesn,t tend to flow as consistantly as below that range.
I stated elseware my current 383 has 36 lb injectors and I need to swap to 40-42 lb simply because the 36 lb are running up near 90% on the current 383 at max rpms
Im just trying to prevent you from needing a second set of injectors with minor upgrades in the future on your combo, heres some calculators to play with

http://forum.grumpysperformance.com/...hp?f=55&t=1200

http://forum.grumpysperformance.com/...0&p=2031#p2031

http://forum.grumpysperformance.com/...php?f=52&t=796
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" IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"
Old 04-22-2009, 12:56 PM   #10
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I don't know, What would your recommend? I want the least way of resistents
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Old 04-22-2009, 02:30 PM   #11
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Here's my take on this. First, let's crunch the numbers.

We have to make some assumptions here. So assuming there is a 18% drive-line loss, and in using the low end of your power goal (400 HP) you'll need right at 490 HP at the crank to get 400 HP on the ground.

In rounded numbers, 490 HP less 88 HP (18%) equals 402 HP

To make that kind of power, while at the same time maintaining the "I want it to be like stock " ain't gonna happen." At least not in normally aspirated configuration without a power adder (NOS, SuperCharger, Turbo) and while maintaining the current cubic inch displacement.

In order to make that kind of power, you'll need to move the current engine's power range from the low-end/mid-range (which is where your current power range is) to mid-range/high RPM range. So in doing that, the engine won't be ". . . like stock". You'll need a dramatic increase in the engine's ability to breathe.

Since horsepower is a caluclated number, not measured, and since horsepower is calculated by Torque/RPM and the mathematical constant 5252, your new mods must be able to make a LOT of torque at the top of the RPM range. Something just over 425 lb/ft of torque at 6000 RPM would be needed; at 6500 RPM you'd need just under 400 lb/ft of torque. (Someone check my math on this).

Making that much torque at those RPMs, without increasing the size (CID) of the engine/power adder, will necessitate a big shift in the power range. Shifted UP the band.

This shift will definitely cause the low end power (torque) to fall off dramatically which translates into the engine not remaining ". . . like stock". You could swap rear end gears to bring back some of the snappiness, but I'm only considering the engine here.

Bottom line is, it's a trade-off' you lose something to gain something.

Now, if you change your goal to something like 400 HP at the CRANK, then the resulting engine will feel more like stock, but still won't be "just like stock". However, the difference won't be nearly as great. Remember, you'll still be asking the engine to put out around 155HP more than stock; 245 Vs 400.

So my thought is, that since you're looking to retain "like stock" characteristics, you'll need to lower your sights or up the cubes.

These are just my thoughts.

Jake

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