I like 540 For the gasket sealing and simply because you get potential cleanups on bore if something happens and you need to bore out.

that seems like way more head than you need for those numbers. It may work better on a big bore but boost will make up for it and you’llhave no issue making that power

i have some ported dart 345’s, on my 555. Twin cast s480’s. So far its made 1602 at 23 psi. I think it has 1800+ in it by time i max the 3 bar sensor. All under 7000 rpm to boot.

 

540 is the largest I would recommend and to be honest I prefer to be smaller than that. You do not need the displacement on a well thought out turbo engine. I prefer to stay between 509CID and 525CID which is 4.00" or 4.125" stroke and a 4.500" bore. Better ring seal, more area for gasket/hoops or o-ring and less piston speed. Piston weight and speed needs to be strongly considered when really leaning on one of these engines running aluminum rods and steel to a lesser extent. All of the mid-frame Pro Mod turbos were designed around peak performance being paired with a 526CID engine. Another reason I like the slightly smaller displacement engines. This also applies to trying to run S400 based turbos on a BB as they are a bit turbine limited compared to the Pro Mod mid-frames. Finally if you are trying to run a small tire, especially a radial why add even more torque from the longer stroke to an already tough to manage torque curve. All the super short stroke blown Hemi guys do it for a reason. The 15 - 40cuin difference will have no effect on ultimate power of the engine and it will be better in almost every possible measure. Hope this helps.

 

Hey Turboll thanks for the response definitely some helpful info. I do believe I'm leaning towards a 540 or as my engine builder says a 538. I'm not limited on the tire as I don't run in classes or anything mainly a fun hobby and my car as we speak now is sitting on a 31 by 16.50 et street r and I think I'm moving to a 31 by 18 et street ss. I do appreciate all the info though will talk more with engine builder and come up with a solution but I don't anticipate going over a 540 just that the heads I'm gonna use they recommend a bigger bore so maybe I need to consider a different head than the headhunter 395. I know a few people with some good running 565's in turbo applications but for me I don't need it I don't think and would like the motor slightly safer even though a lot of the good engine builders are saying it won't matter thanks again.

 

Some heads, especially the MC(moved centerline) heads, SR20 etc need the extra bore to make the flow from unshrouding the valves. In SOME cases it may be able to clearance the edge of the bore enough to run them on a 4.500" bore without any other clearance issues. This is commonly done on 481X and Hemi Pro Mod engines. As long as you can. Stay out of the hoop/o-ring area its no problem. We're talking about a canted valve head that gets the valve head further from the bore the more it opens and were only talking .050" per side bore difference so taking that off the corner of the bore IS doable in many cases and the boost will take care of whatever small penalty is due to shrouding the valve a little. Just options to consider and must be verified by mock-up. Good luck with it and keep us updated.

 

Thanks again man very much some great info this will be my first BBC and hoping to get in the 7's using about 80% of the cars power I like to be safe just me but again some great point I'm all ears and eyes I should say on this matter from the great experience on this site.

 

Making power isn't going to be an issue. I'd be more concerned with picking a head that excepts a good rocker arm assembly for valve train stability. Also, a head that offers HIP cast processing for additional strength. As mentioned, a 4.5 bore would be the way to go for trouble free sealing with hoops. If you're looking to make 2200hp, you'll probably be turning it up to 2500hp so overbuild from the start.

Like you, this was my first BBC build so I did a ton of research before choosing parts. My little 477ci made 3,100hp.

 

the best turbo BBC motor i ever did was a 632ci... had no issues holding gaskets in at 60+psi...

 

What kind of heads did you use on that? The bigger inches tend to help in bracket racing get things moving during the short staging process. So that big guy would be great. And at 60 psi, that was making power!

 

Build what you want.
bore - depends on head /valve shrouding
Stroke - depends on tire height/ mph intended to run. Every class has a top mph car and ET champ.
Wins-depends on power management. 😁

All combos are naturally aspirated before screwed, blown or hair dried.

 

I kinda wish i went 4.5 stroke because my turbos are more rear mounted. Woulda helped getting them lit but i would feel i needed more head as well. 2.35 valve for 7000-7200 rpm. Mine are 2.30 and around 355-360 cc

 

I have often been baffled with the smaller is better when it comes to turbo engines deal. I understand there can be practical issues with sealing etc. But nothing covers up a soft low rpm like more cubes. And nothing makes the turbos spin more quickly than more volume.

 

Well guys thanks for all the input and yes block and heads will be hipped as we speak looking at the hip cost of about 1k for heads and block. Thanks again Lowwlife for the input yeah don't think I will turn it up to where your at for sure but also curious what you run for turbos on that 477 yeah your making power. I will say to all of you that chimed in thank you still don't seem to have a real concrete answer. I think my engine builder will make it work with a 540 or 565 and I may look at a different cylinder head it doesn't matter anyway because no heads look available till April. I do think a 540 is where I will settle.

 

I run Garrett Gen2 88's.
Good choice on the hipped block and heads.

 

Yeah Lowwlife you making a boatload of power I've never been in that area like I said maybe 83's for me but thought of 81's but what's the difference have some room for more with 83's but yeah 88's is for you big boys lol.

 

After reading post about different engine sizes, I pulled a few dyno sheets to look at.

First is a 540ci BBC, Brodix HH, Precision 88's, 800lb injectors on methanol.

Second is my 477ci BBC, Edelbrock Victor Jr, Garrett 88's, 800lb injectors on methanol @ 7600rpm.

 

Yeah those are big numbers for sure like I said I'm simple it's just a very very part time hobby for me now as I work a ton and have 50 employees. I'm looking for something that will make 1600hp on pump gas and 2200 on c16 no meth or meth kits something simple and fun you can load up and go to the track and also hit a cruise night with the boys and have a few burgers and hopefully a 7sec slip in a true street car

 

Shouldnt be to hard. Mine made about 1200 at the tire on pump gas tune but may be more in it, just no reason to push it since i have e85 every where. That was like 12-13 psi.
it made 1600 on 23 psi on e85. On 21-22 psi short shifting first andsecond by accident it went 8.20 at 178 at 4000 lbs and a crap 60foot. Basically in third gear from 330 on lol. Never got to make a good pass with it, trans and rear issues. But no doubt an easy 7 car. You shouldnt have any problems

 

my old shitter 548 made 3476 at the wheels, it was a big m block, cast brodix BBX3's with some hand porting.. went near 190mph to half in a 3200lb car, im sure i could have run 3.95@195 with it if we didnt get covid shut downs right at the start of that season...

 

Hub or wheel dyno?
Nice lap for sure!

 

Working on a 598(4.600x4.500). Might work better at 4.500x.4.500 but the heads need a 4.600 bore with a 2.500 valve.
Hoping for 3500@8K. I'm in the longer stroke, bigger C.I. camp. Proven build. Should be very reliable. That's key.

 

Working on a 598(4.600x4.500). Might work better at 4.500x.4.500 but the heads need a 4.600 bore with a 2.500 valve.
Hoping for 3500@8K. I'm in the longer stroke, bigger C.I. camp. Proven build. Should be very reliable. That's key.

You have more spec’s on your combo looks like a good one

 

Wealth of Knowledge from you guys for sure I'm building a wimpy motor compared to you guys but actually it's just a turbo swap away from being what I call crazy but I will grow into it easy 3500 at the wheels impressive for sure

 

10sec_Rx7, any updates on your billet combo? I follow you on IG but haven't seen anything as of late.

Yeah, that last combo dyno pull from summernats 32 was nuts.

 

we have been shut down for pretty much 2 years... we did a few shake downs with the billet motor, had some oil issues sucking in the valley, fixed all that, drove 12 hours (march this year) to a race meet then broke the diff housing, dodgy fixed that up at the track and then got 150ft out and smoked the tyres lol.. new diff housing is in and car got scaled and setup yesterday as we were suppose to test on saturday but that has been canned as well and now its going to be hot as fuck for the next 2 months its pointless going out..

 

Good to hear the new combo is up and running. Keep us posted.

BTW.....give your fabricator/tig welder a pay raise. That dude is Badass!!!

Sorry for the highjack OP

 

Good to hear the new combo is up and running. Keep us posted.

BTW.....give your fabricator/tig welder a raise. That dude is Badass!!!

Sorry for the highjack OP

yeh he goes pretty damn good on the welder,

have done a heap of other stuff including new wiring and a rossler 3 speed etc, so its a pretty much whole new package again lol

 

its not a dynocom lol... the mainlines at that power read pretty good, it was the 6000hp version