View Full Version : totally one-off 3800 build research
09-16-2010, 06:36 AM
Hey, all. I realize the bias towards SBC and BBC here, and I realize it would be SO much easier to build a SBC to my goal of 400-500 WHP, but none of that is the point. This build is a tribute.
I intend to take a short-block 3800 (not sure if I want the L36, L67, L26, or L32 block yet), punch and stroke to 4.3L and make at minimum 400 WHP. I know theres a lot to this that I need to learn and comprehend before even buying the junkyard block. The questions I know I need to learn are as follows, and am looking for everyone's input on what else I need to learn about:
block-specific max bore
block-specific max stroke
valve clearances and tolerances
effect of different firing orders/balancing the engine
cam theory and timing
materials best suited for each location in the engine
timing gears or chain
exhaust theory and evacuation
high-velocity n/a induction
choosing the appropriate flywheel
choosing the appropriate clutch
choosing which gear ratios inside the 6-spd transmission
choosing which transmission to start with
choosing the appropriate driveshaft
choosing a good, general-use final ratio
LSD or Quaife LSD
OE differential size or 10-bolt/12-bolt
IRS or solid axle
The timeline for this project is expected to be greater than 5 years at a drivetrain cost of at least $15,000, although $20,000 is expected. The suspension set up is something that I think I can dial-in myself for about $2,500, and the appearance is expected to be about $7,000.
Thank you one and all for any additional questions you can help me find or any resources you can point me to.
09-16-2010, 12:55 PM
The questions I know I need to learn are as follows
You didn't ask a single question in your entire post. People don't volunteer info, you must ask the right questions to get the info you need.
09-16-2010, 02:40 PM
Might I recommend you join FullthrottleV6, we'll take care of you over there.
But I'll try and toss in my $0.02 for you. Answers within your quote will be bold and off color.
I intend to take a short-block 3800 (not sure if I want the L36, L67, L26, or L32 block yet)[these blocks are all the same],
punch and stroke to 4.3L and make at minimum 400 WHP. I know theres a lot to this that I need to learn and comprehend before even buying the junkyard block.[Stroke is fine, $3000 for just the rotating assembly + machine work and supporting parts. Boring these engines isn't going to net you much of anything, we don't have enough material in our cylinder walls to play with to make it worthwhile.
400hp NA, or power adder?]
The questions I know I need to learn are as follows, and am looking for everyone's input on what else I need to learn about:
block-specific max bore, block-specific max stroke,piston-to-wall clearances [Let an experienced machinist worry about these. COME racing offers a stroker kit which comes out to almost the maximum amount that we can run on these engines]
flame propagation [don't worry about this]
valve clearances and tolerances,deck clearance [Machinist]
effect of different firing orders/balancing the engine [The stroker from COME is balanced, I'd recommend an ATI front balancer, not sure on the flexplate/flywheel.]
cam theory and timing, materials best suited for each location in the engine [Machinist & Also how you intend to make the power.]
timing gears or chain [Big valvesprings and high lift cam needs a double roller timing chain. You can do 130# valvesprings on a single roller though]
oiling [There are many things that can be modified to improve oiling to for this engine. Mostly involves opening up the galleys in the crank and cam tunnel, porting the passages in the oil pump and filter adapter along with blocking off the filter bypass (these stick open on high mile cars and wash the crank in unfiltered oil, leading to a spun bearing).]
fueling [Depends on how you want to make the power. A Walbro 255 could do just fine initially, or you might have to go to a larger setup like an aeromotive pump. Also will need bigger injectors as the stockers are only 19lb rating.]
ignition/spark delivery [Stock coils work just fine, and are more reliable than the MSD coils.]
tuning [HPTuners and a good wideband, no other excuse if you're serious about your car.]
exhaust theory and evacuation [My theory? Use a 3"cutout, run a good catback after that. If you're going NA/Nitrous/Supercharged, Longtube headers (Force Fed Fabrications has them for the 3.8 F-body), turbocharged will require talking with a vendor about your engine setup as a whole and have one or two turbos sized accordingly.]
high-velocity n/a induction [Holden Intake Manifold, longer runner design and easier to port the whole thing.]
choosing the appropriate flywheel, choosing the appropriate clutch [Depends on power output and delivery.]
choosing which gear ratios inside the 6-spd transmission [Car comes with a 5-speed, so you're converting to T56? Leave the gearing alone and adjust the final drive on your rear end for appropriate power delivery. You'll need to use a T5 bellhousing, clutch and flywheel, adaptor plate, shortened driveshaft, etc etc.]
choosing which transmission to start with [Looks like you were going with a T56 in the previous statement.]
choosing the appropriate driveshaft [LS1 aluminum DS is fine, but if you're spending coin on everything else, get one that is properly designed for your output.]
choosing a good, general-use final ratio [Depends on what power and how you're getting it. NA/Nitrous/Supercharged like something above 3.42, while Turbocharged like a little more load to help spool.]
LSD or Quaife LSD [Look through the vendors, find one that is the proper carrier series.]
OE differential size or 10-bolt/12-bolt [You have a 10-bolt, not many V6 guys have 12 bolts, depends on if you run a manual or auto. Manual + power, you might want a 12. Auto is fine with 12-bolt.]
IRS or solid axle [Solid axle, add Watts link.]
09-17-2010, 12:59 AM
3.4 Camaro: I had stated what I already knew I had to learn about. The point of this thread was to have folks tell me the other stuff that still eludes me.
Warshrike: Thanks ALOT for your answers, that was what I WASN'T expecting. Expect to see me over there within the next few days.
Indeed, I do intend on staying N/A. My brother believed in freeing up what was already there, not "cheating", as he would put it.
Great thing about tuning: I already have the PowerTunr, and am already eyeing widebands for the GP AND Camaro.
Transmission has me curious what all else is out there. T56 is GREAT, I already know they're cannon-proof, but is that what is most appropriate for my application/build? I have a few years to research that question.
What questions have I still yet to consider to achieve 4-500 WHP from over-sizing a 3.8->4.3?
Thank you again for the unexpected help!
09-17-2010, 08:21 AM
Okay, 400hp NA on this engine is lofty, but who knows. If you have the spare cash for this then you could work towards it. We have stock eliminator cars in the 11's with ~280whp.
Biggest barrier is going to be the cylinder heads. Our heads aren't the best flowing design at all. Stock at max lift you'll see something like 150cfm. Worked heads like Abbott's stage 3 heads will flow over 200cfm, but that's with a lot of porting, big valves etc. etc.
ZZP has aluminum heads that have some better characteristics, but they'll still need to be ported and worked on by a skilled person to get the best out of them.
NA, you'll want higher compression (stock is 9.3:1).
You'll need a cam spec'd properly for the stroker motor, and will need one with quite a good bit of lift with worked heads to get as much air as possible.
Large valvesprings and double roller timing chain.
The list goes on.
09-25-2010, 07:07 PM
You might be interested in this article, not exactly what you're thinking about doing but similar.
10-01-2010, 02:25 AM
The highest rwhp with a 3.8L is about 270-275hp and that was with high compression/bigger vale heads, cam , and all bolt ons.
With a 4.2L/4.3L stroker kit which is around $3000 for a kit will add roughly another 50-60hp but that will still be far from your NA goal without nitrous.
I don't think 400rwhp will be possible in that engine since that is double the flywheel power stock too.
10-03-2010, 09:44 AM
they made some 3.8 turbo cars that made serious power, that would be your smartest most economical route.