318 stroker -> Mopar Performance A8 build guidance needed.

[SOMMS]

worrying about engine weight should be your last concern. i think that 50lb difference between the small blocks is hogwash. and that 200ish or so for an A8 when you break down for $ per pound is a poor investment in weight reduction. your return for dollars spent in lightening something up would be so, so much more on a fiberglass front clip, gutting the interior, lightweight wheels/brakes, aftermarket K setup, manual steering, alum radiator, that sort of thing.

TT5 had the answer-- lose 50lb someplace else.

unless you have or are planning on getting a car that is "correct" for that 340 and you care about "numbers" then i wouldn't even consider it as an option and sell the thing to finance another aspect of the build.

also, "8K for an A8" is not even close to being a reality. that's just for the block man. then, before you can even thing about putting stuff into that block you're gonna need sleeves (i don't think the block comes with them) so there's another 1K, a timing cover (1,300), headstuds (1,100), misc. block hardware/cam bearings, waterpump drives, plates and **** (1,000), dry sump oiling system (2K WAG) so that's about 15K before we're talking about machine work, heads, intake, and a bottom end (cranks are what, 5K?)...

random question, what's your overall budget for this build? what do you project the timeline to be?

Junkyard hero - thanks for the input. All that stuff is already slated to be done. The plan is: fiberglass hood, manual steering, qa-1 (or the like) k member, battery relocation, alum rad, as lightweight wheels as can be afforded. Rylispro (https://www.youtube.com/results?search_query=rylisprois) is running something similar and still is only getting 52/48 front rear weight distribution. However, he's running the Gen III hemi and stock K-member.

 

[junkyardhero]

i think you're approaching this from an obtuse angle. first of all worrying about or trying to get to a 50/50 weight distribution in any car that is not a dedicated race car is an endeavor of foolishness.

second of all, think about all the peripherals needed to support a romping stomping machine: you'll need subframe connectors and body bracing, which is a known entity. but people don't take into consideration that a full road race oil pan weighs significantly more than a stock pan, as does the extra oil you'll have on board for the oil cooler, and hopefully your accusump, then you've got the fuel bits, plus all that AN line, remote mount filter(s), and plumbing.

on a race car you can, to a point, pick and choose where to move that weight. with a "street" car you're not really afforded that luxury.

you can turn a cucumber into a pickle, but you can't turn a pickle back into a cucumber; so sometimes it's just better to make relish with it.

 

[273]

Do you plan on competing competitively ? Doubt most the top guys are dual purpose. and if your fine with a less competitive car you could dial it back, handling matters more than power, especially in a parking lot autocross no long straight aways, lot of power that's a lot work and experience to get it to hook.

1st I'd forget about top end hp, what are your trans gear ratios what gears your gonna spend most of your time in, probably only one or two of them in a autocross, figure what rpms you will be turning at the speeds at most events. Especially what rpm you will come out of the average corner. Then there's how much power you can reallistly hook out of the corners.

Say it's 3000-5600 rpms, your gonna spend more time in the bottom half of 3000-4300 rpms, thats 58% to 83%, hp% of tq, so say you build a fairly high 1.3 lbs-ft per cid at peak tq and flat in that range of 3000-4300 rpm ,

At 1.3 lbs-ft per cid a 396 = 515 tq = 58% 299 hp @ 3000 rpm to 83% 427 @ 4300 and about 486 @ 5600 rpm.

Lesser lbs-ft per cid which is where most average guy builds live will make less power and obviously more makes more, same with less or more cid, at 3000-5600 rpm.

 

[Killer6]

Lessee - I'm using the one posted at Hughes Engines (https://www.hughesengines.com/TechArticles/5engineweights.php). And aluminum heads are going to be used no matter what (trick flow v W9).

That puts the 318/340 in the 475lb zone(with alum heads).

While those are still "approximate from various sources", the relative differences are the same, dressed or assembled long blocks. I considered what You are only using the "R" block LA version, but unless it's going to make $$$$ for You, the return isn't worth it for the weight savings.
I wouldn't buy the trans until You've actually decided on the mill, torque band/rpm range should be known so the gearsets & rear gears can be picked to compliment them.
Might want to peruse Racing Junk for old ARCA NAPCAR or other series stuff where Mopar pulled out long ago, it went somewhere, l would go with as much displacement as possible if You want this project to do some kind of dual-duty at that output level.
Best of luck.

 

[SOMMS]

i think you're approaching this from an obtuse angle. first of all worrying about or trying to get to a 50/50 weight distribution in any car that is not a dedicated race car is an endeavor of foolishness.

second of all, think about all the peripherals needed to support a romping stomping machine: you'll need subframe connectors and body bracing, which is a known entity. but people don't take into consideration that a full road race oil pan weighs significantly more than a stock pan, as does the extra oil you'll have on board for the oil cooler, and hopefully your accusump, then you've got the fuel bits, plus all that AN line, remote mount filter(s), and plumbing.

on a race car you can, to a point, pick and choose where to move that weight. with a "street" car you're not really afforded that luxury.

you can turn a cucumber into a pickle, but you can't turn a pickle back into a cucumber; so sometimes it's just better to make relish with it.

"I think you're approaching this from an obtuse angle."


I could not agree with you more junkyardhero.

The point of this effort is to try to get as close to 50/50 as possible (without relocating the engine too much). I want to keep the body as near as unmolested as I can get. Yes, there are folks in Sweden who'll cut the firewall, move the motor back 8 inches and get 50/50. But they have to cage it and jettison the back seats. I'll move the motor back some...but I aint cutting the firewall. Ditchin the firewall and backseats is poor form for what I'm going for...hence my interest in an all aluminum small block.

 

[SOMMS]

Do you plan on competing competitively ? Doubt most the top guys are dual purpose. and if your fine with a less competitive car you could dial it back, handling matters more than power, especially in a parking lot autocross no long straight aways, lot of power that's a lot work and experience to get it to hook.

1st I'd forget about top end hp, what are your trans gear ratios what gears your gonna spend most of your time in, probably only one or two of them in a autocross, figure what rpms you will be turning at the speeds at most events. Especially what rpm you will come out of the average corner. Then there's how much power you can reallistly hook out of the corners.

Say it's 3000-5600 rpms, your gonna spend more time in the bottom half of 3000-4300 rpms, thats 58% to 83%, hp% of tq, so say you build a fairly high 1.3 lbs-ft per cid at peak tq and flat in that range of 3000-4300 rpm ,

At 1.3 lbs-ft per cid a 396 = 515 tq = 58% 299 hp @ 3000 rpm to 83% 427 @ 4300 and about 486 @ 5600 rpm.

Lesser lbs-ft per cid which is where most average guy builds live will make less power and obviously more makes more, same with less or more cid, at 3000-5600 rpm.

Thanks for these questions 273:

I am looking to race low-key competitively - I want to throw down at our local track (Pacific Raceways)...but I am not quitting my day job or traveling more than a couple hundred miles. This is not an autocross rig - will be mixing it up on actual road course tracks with other cars. Haven't totally figured the class out yet - can't be 'vintage' because that requires all the stock running gear.

And again - I don't actually care that much about hp, as long as it reliably makes something north of 500 and is as light as possible. Hence the a8 questions.

S

 

[273]

Thanks for these questions 273:

I am looking to race low-key competitively - I want to throw down at our local track (Pacific Raceways)...but I am not quitting my day job or traveling more than a couple hundred miles. This is not an autocross rig - will be mixing it up on actual road course tracks with other cars. Haven't totally figured the class out yet - can't be 'vintage' because that requires all the stock running gear.

And again - I don't actually care that much about hp, as long as it reliably makes something north of 500 and is as light as possible. Hence the a8 questions.

S

Time attack is a solo race on a road courses. I think your to over focused on the 50/50 weight distribution, what real world benefit in track times are you gonna see with an iron vs aluminum block ? And if your fairly new to this, your driving is gonna be where you find the huge gains. The engine block sits low and mostly behind the front wheels, the extra weight there isn't as much of a problem then higher weight eg.. glass windows etc.. and pass the front and rear tires like bumpers and hood, trunk lid, is under both. The A8 seems like overkill and if you got that much money just build two cars instead of compromising, one mainly for the track and one for the family.


I see you don't want to cage it, which I get but that's gonna be more of time killer added to other things that you won't change which makes the 50/50 make less sense. Plus The power you want to build is probably gonna require some roll protection especially on a high speed road course.

I'd get rules before make any big plans.

Your plans are probably set in stone and I don't know your past autocrossing experiences but nothing wrong starting more modest and slowly move up, gaining experience in driving and what it's gonna take car wise, there's a few here who autocross and I want to do some myself, they got nothing close to what your talking about, hopefully they join in.

 

[junkyardhero]

I am looking to race low-key competitively - I want to throw down at our local track (Pacific Raceways)...but I am not quitting my day job or traveling more than a couple hundred miles. This is not an autocross rig - will be mixing it up on actual road course tracks with other cars. Haven't totally figured the class out yet - can't be 'vintage' because that requires all the stock running gear.

And again - I don't actually care that much about hp, as long as it reliably makes something north of 500 and is as light as possible. Hence the a8 questions.

make no mistake that a dual purpose street/track car is going to get absolutely curb stomped by any dedicated track car, no matter how much power you're making. it won't be competitive, not by a long shot.

pretty much any kind of organized on track racing will require some type of roll over protection-- track days usually do not, but you can be asked by the track or organizer to leave if you're running real fast with no safety equipment. that's at their discretion.

500hp is doable, and i think you can make it reliable but it's going to be expensive. not A8 kinda coin, but more than an average hot **** street motor.

my concern is that you're so fixated on weight and 50/50 that you're missing the broader picture.

one last thing: you're building an E body, why are you asking us? them dudes should be knowing all about it over on FEBO

 

[9secRR]

A friend of mine has 2 A8 aluminum blocks with W8 heads. One is 414” and the other one is 477”.

He also has this block for sale and the cam drive for it

 

[Scody21]

Look up an SVRA race which is vintage racing at PIR or PAC Raceway. There will be TransAm cars which you can get up close to and take photos. With what your thinking, doing track days, which is not racing or doing solo autoX or time attack is a better option. Being out in a non caged car full on racing with other cars is a death wish. Build a street car or build a race car. Not one in the same. And what happen when ya stuff it in to a wall cus your brakes faded and you drove it to the track that day?

 

[DNasty777]

I don’t think any sanctioned series allows for wheel-to-wheel racing without a certified cage. NASA and gridlife certainly dont.

 

[Killer6]

Thanks for these questions 273:

I am looking to race low-key competitively - I want to throw down at our local track (Pacific Raceways)...but I am not quitting my day job or traveling more than a couple hundred miles. This is not an autocross rig - will be mixing it up on actual road course tracks with other cars. Haven't totally figured the class out yet - can't be 'vintage' because that requires all the stock running gear.

And again - I don't actually care that much about hp, as long as it reliably makes something north of 500 and is as light as possible. Hence the a8 questions.

S

This is a '72 E-body 'cuda?? Why are You foolin' with exotic SB stuff, when a stroker B engine w/good aftermarket heads will make plenty of oats, & there are Al-U-minimum blocks out there as well. A 512 will make 650 falling off a log & be twice as streetable. The stuff You want to run isn't going to be cost effective at all, and 50/50 is gonna be impossible on a street E-body w/o butchery.... but I don't know what You consider acceptable to do to it....