So as in OK Rods 408 makes about 500 with 195s, with an RPM intake, and a Voodoo HR 282 cam, it falls over at 6000rpm or there abouts, so on a smaller engine with a victor type intake and a bigger SR cam it will rev harder than the 408 but how much is the question, and it will need to rev a bit hrader to make up the missing 58 cubes to make the 500. they are not optimum but will work. So if budget is an issue I'd tidy them up and give them a go with suitable spring to suit cam choice, its only an after noon to swap them out later when you can afford better ones.
Last edited by Shaunp on Wed Mar 08, 2017 3:39 pm; edited 1 time in total
Look at the heads from a theory point of view.
The Dart heads have a ACSA of 2.392 so they will be done by 5768 rpm in a 351 engine.
That is simply not enough RPM to get you to 550 HP.
So a 351 needs a ACSA of 2.894 to feed enough air and not be to fast at 7000 RPM.
So to compare at TFS 225 high port has a ACSA of 2.615 which is not big enough. Though it would work ok because the highport can handle faster air while most do not - all due to the port position changes and shape.
You will need 7000 rpm to get or pass your target HP.
I define OK as
* It is worth spending the money now to buy the rotating assembly for the 51 with the heads I have
* the 51 engine will make reasonable power- 500 at this stage will be fine
Another question to ask:
Spending $800-odd on the Dart heads is putting my investment in these heads at around $2,400. This compares to buying new TF heads at about $3,000AUD or 20% more. Will the Dart heads with work come within 20% of the performance of the TF heads? Will they come to within 10%?
There's another issue I have which I only found out today. I have a TKO600 box which the internet tells me gets unhappy over 6,000 rpm and refuses to play. The 347 is limited to 6,000 +/- by virtue of the block. The 351 will go to 7,000+ but then I need to upgrade the box; and a Holinger dog box is $20,000.
So, the challenge is - lets limit both motors to 6,000 +/-. What would be the power difference between the 347 and 351 at those revs and what needs to be done to achieve that?
It's a compromise but the LS1's (hack/spit) look like they are making around 550 with TF top end and FAST injection. The ones with Harrop induction are probably pulling more. I need to compete with that. I really don't want to put $6,000 per year of my own money into a car to come in behind a bunch of Chevadoors.
So to give you what I have now this is the list:
5.0L roller block - Bronco or F Truck
Scat 9000 crank
Scat steel rods
Voodoo 282 HR (?)
Probe 4cc flat tops
Dart Pro 1 heads - 2.02/1.60 195cc
RPM air gap
AED 650 DP
stud girdle/windage tray/scraper
dual roller chain (non adjustable I think)
Used complete injected engine from an F Truck
Last edited by smh00n on Wed Mar 08, 2017 7:11 pm; edited 1 time in total
The Australian Trans-am 351s may be a guide, they run them to 7k, run a Victor, the rules allow max compression of 11:1 , cam is free but they run a decent SR cam,. the heads are restricted to 200c inlets, but what most of them are is 190/195cc ports that they port to 200cc, the rules allow for bowl blending and port matching a certain distance up the port, so this is how they get the 200cc, all the fastest ones run custom tuned headers and side pipes are standard. Max bore size is +060 Some run light weight rotating assemblies, such as Callies, but most just use 4340 Scat. They are super reliable and quite fast, they typically freshen them in the off season, rings bearings chain, lifters that is about it. Im not sure if they are permitted raised exhaust, I'll have to look at the rules.
I think my restricter will be the box and the 6,000rpm.
Encouraging on the heads but, the engine guy has a flow bench so he should be able to make them work a bit better.
Building the 51 might be better simply for reliability of the block?
Re the gear box, I think most of the guys use a G-force box in the T/A car, you can get them as a dog or syncro. and several ratio sets. I think they are less much expensive. You cant get the HP you want with 6Krpm. Perhaps call Woody he used to stock the G -force boxes.
Does it have to be 5 speed? you can dog box a toploader if you want, I think Liberty still do a dog box kit at least they use to. Other option is maybe t56 magnum surely they can take 7k they are very strong. If you can afford other heads Id buy them, I'm not a super fan of the dart head other then they are ok value when the were like 1600 a pair. Woody generally uses Brodix on the TA cars that he ports himself. Having said that If you can afford some TF or AFRs in a raised port that is the way to go. Talk to your bloke as to what he will charge to port them, but be mind full not to get in too deep with them. You'll not be running it at 7k in real terms most likely you'll be up there a bit though. Don't under estimate the exhaust , I know they often muck around with the pipes on the 302 TA engines to find the sweet spot. They are permitted to rev to 7500.
Last edited by Shaunp on Wed Mar 08, 2017 10:07 pm; edited 4 times in total
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