had some bad luck last saturday at the track. Lost all oil pressure and motor started knocking at the end of a pass. Immediately shut the car off. wasnt leaking anything. Had a friend with a shop and lift come pick the car up. he just sent me these pics.








so now ive got some decisions to make. Ive been doing research every day for the past week as to what my options are. Like most others im on a tight budget. I know the price difference between the 347 rotating assembly and the 408 arent that much. But then you have to consider the new block price and whatever else ill need to get a 408 going.

- Use my block for a forged 347 keeping my heads / cam and hit it with a 200 shot. ( MAYBE go with a different camshaft?)

- Buy this 6.0 shortblock ( 40k miles ) for $650 and go with a 408.

im not sure how much the machine work is going to cost on either of these. Or what i will need to replace on 6.0 shortblock other than the crank / rods / pistons. Id probably want a different cam for sure. would my heads be ok to use on a 408ci motor ( tfs as cast 220's )? I just dont want all the little stuff to start adding up and me end up having quite a bit more than id like in a motor. Any idea of a ballpark price i could get a complete 408ci motor put together???

 

If you can't afford the proper top end for the 408, then the forged 347 with the 200 shot sounds the best to me.

 

l92's are affordable and seem to be used on other builds. as for intake / tb. i could get partially there selling my ls6 / stock tb.

just dont want to be wishing id gone bigger if i went 347.

 

Yep, I'd regret it also. But the 4++ motors don't seem that great when the top end isn't done right. Though torque will increase the max hp isn't that impressive when they can't breathe properly.

 

Yes there are better heads for a 408 but mine almost makes 500rwhp with those heads and with a little tweaking I sure it would break it... you could prolly sell your whole topend though and go l92 for not much out of pocket. It's a gamble though because I have seen some really impressive L92 combos and some no stonger than mine. As far as the casting the TFS is better and has a better valve angle too..

Having said all that if you can spring some ported L92's it should pack a bigger punch...

 

That's why I'm considering going to a 408 because it may not be out of reach for me from a financial standpoint if I do go l92 but then again it's still more money than just getting rods / pistons for a block I already have. This is difficult.....

 

If it were mine and the thought of "tight budget" came up what so ever, I would get forged rods/pistons and put your current engine back together with those.

 

Well I could handle having $500 more in a 408, but if it's $1000 more then no. ( just an example. No idea of a price ). Selling my tfs heads / ls6 intake / stock block would free up some more funds towards it.

 

If you are talking 500, then thats a big no. The small **** catches up with you quick.

Why not go 383 then since you have the money for a stroker kit and you could re use the block you have and your TFS 220's will work good on it.

 

Hahahaha that's crossed my mind also. There are so many possibilities. Maybe I should ask my 10 bolt for advise

 

I feel the same about that. Having extra cubes is cool and all but if the top end cannot support it, your wasting fuel.

 

Definitely do a 383 if your block is good enough to reuse. A few extra cubic inches won't make that big of a difference, especially without a maxed out topend.

If you had absolutely killer heads/intake/cam then yeah the extra 25ci would make a good bit more to be worth the hassle of getting a new block and selling your old one. But with your basic setup it would be more beneficial to just do a stroker in the current block. You won't be down more than 20-25rwhp over the 408 and save you from having to deal with buying a new block.

 

Well I have a different outlook for you to consider as well. I am a 6.0 fan thru and thru. I put a stock bottom end iron 6.0 with arp rodbolts together with a ported set of 5.3 heads and a healthy cam and put 447 to the tire through a th 400 and 4000 stall with a 12 bolt! 10.81 @126. If you can get the 6.0 short block, drop rings, rod and main bearings in it with some arp rod bolts and throw the trick flows on it it will run!! Compression around 11:1 perfect!

 

ok i thought creating a thread would help me decide. its not! i guess if having an average top end on a 408 and making mid to upper 400hp compared to re using my stuff and making low 400hp is something i didnt think about. id be saving weight as well as money.

 

A proper built 383 with TFS heads should not be making 'low 400hp'. That's cam only 364 territory right there.

With your heads and a properly matched cam you should be in the high 400s with the 383.

 

383 ls1's run like a **** ask me how i know...lolol the 383 in my sig with good air/ low humidity puts down a little over 500rwhp N/A. before this i had the 383 bottom end, asp underdrive pully, roller rockers and a 581/588lift- 224-228 duration cam, on STOCK HEADS(241), STOCK INTAKE MANIFOLD(ls6), AND A PORTED STOCK THROTTLE BODY, with ARH long tube headers,and a lid. And in the humid summer air the car put down 433rwhp and 434rwtq. but a broken timing chain killed the top end so i rebuilt it to its current status.

 

I was meaning a 347.


I haven't really done much research on 383's or looked at performance / results. I guess I'll have to get to work.

 

well if you drag your car alot and you go with big cubes your 10 bolt is on borrowed time just remember that.


If you are on a budget you really want to stick with the block you have, engine swaps get up there fast in all the little small stuff. the cheepest engine swap you could do is pull a LQ9 out of something and throw a cam in it with your heads.

its a touph decision for sure. but keep in mind big cubes are not always the best bang for the buck. figure out your HP goals first and remember if your on a budget you dont want something that your rear end cant hold. FWIW a forged 347 can easily hit upwards of 500hp with the right combo.

 

just went through all 10 pages with "383" in them. Doesnt really seem AS common of a build compared to a 347. All the guys with them seem to enjoy them though. Id be keeping my heads if i use my block. cant afford anything better and thats money i could use towards and intake / tb after selling mine.

Im really leaning towards using the block i already have. Getting a custom grind camshaft and taking some weight out of the car. If i can get around 420ish hp maybe, with a FAST setup and spray 200 to it, id be happier then going iron block 408 and having more money than im expecting in a motor build. i could put the extra money in a kmember or something.

 

I have seen some 383 run pretty good but also seen some 347 sprayed hard and ran good to. So I am no help.