Big HP on pump gas.

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AA Performance
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Big HP on pump gas.

Post by AA Performance » Sat Jun 23, 2018 5:28 am

Just trying to get an idea on how difficult it will be to get an honest 1000+ hp on pump gas. We have what we call 98 octane here but is rated differently to you guys but I'm sure it will handle around 11.75:1 static comp with a reasonable cam. Would like to get a few ideas on building a BBC to reach our goal for a customer. It needs to be not too harsh on springs and r/lifters. Was thinking on a 10.6 deck block to get a stable piston & ring pack with a 4.75 stroke crank and a decent rod in it with the 4.600 bore.. Was also looking at running the Brodix 16° heads and their single 4bbl intake with some custom spacers. I plan on using a solid roller with the Crane softer .427" lobes with maybe a 1.85 rocker to get some lift. Can I get some thought and ideas on this build. I was also looking at the SR20 head and also the dart 20 with the Reher Morrison port program as they seem to flow heaps. The Brodix have the smallest port volume of the 3 heads but seem to flow the most.
Thanks for any help and advice.

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Re: Big HP on pump gas.

Post by apm » Sat Jun 23, 2018 6:45 am

Built a 750 ci BBC on pump gas , 98 octane, 12.3:1 , bullet ground a cam for me 274/280 @050, 1.75 rockers , 740 valve lift, gentle lobes, only run 240lb on the seat and 650 open ,its a Dart 11.1" deck, 4.7 bore and 5.4 stroke , 4.9 bore space , profiler heads , we made a really short sheet metal intake and use 2 x dominaters, , it's in a 67 2 door impala and has a 2.5" reverse cowl , makes 1100hp and 1000ftlb , peak power is 6700 rpm
I drove it and it actually drove nice but squeeze the throttle and it's like a bomb goes off !

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Re: Big HP on pump gas.

Post by peejay » Sat Jun 23, 2018 9:43 am

It only takes 9-10 pounds of boost in a big inch LS to make that kind of power on 92 octane R+M/2. Legally , our research and motor octanes may not be 7 numbers apart so this is about like your 95 octane at best.

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Re: Big HP on pump gas.

Post by grant6395 » Sat Jun 23, 2018 11:20 am

peejay wrote:
Sat Jun 23, 2018 9:43 am
It only takes 9-10 pounds of boost in a big inch LS to make that kind of power on 92 octane R+M/2. Legally , our research and motor octanes may not be 7 numbers apart so this is about like your 95 octane at best.
Who cares. He wants an n/a combo obviously
What I can't figure out is why people respond with facts and figures that don't even pertain.

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Re: Big HP on pump gas.

Post by Frankshaft » Sat Jun 23, 2018 12:03 pm

Your on the right track. The sweet 16's are more of a nitrous head, I would use PB 2005. Or even a 1203 with porting. Anyhow, the Pb 2005's are better I think than the 16's. For intake, I would skip the brodix and use a big victor 2, its better and looks cooler. They do need A LOT of work to really make power, but will easily support your goal otb. Even the original big victor will. Keep one thing in mind, those blocks are HEAVY.

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Re: Big HP on pump gas.

Post by Headguy » Sat Jun 23, 2018 12:08 pm

AA Performance wrote:
Sat Jun 23, 2018 5:28 am
Just trying to get an idea on how difficult it will be to get an honest 1000+ hp on pump gas. We have what we call 98 octane here but is rated differently to you guys but I'm sure it will handle around 11.75:1 static comp with a reasonable cam. Would like to get a few ideas on building a BBC to reach our goal for a customer. It needs to be not too harsh on springs and r/lifters. Was thinking on a 10.6 deck block to get a stable piston & ring pack with a 4.75 stroke crank and a decent rod in it with the 4.600 bore.. Was also looking at running the Brodix 16° heads and their single 4bbl intake with some custom spacers. I plan on using a solid roller with the Crane softer .427" lobes with maybe a 1.85 rocker to get some lift. Can I get some thought and ideas on this build. I was also looking at the SR20 head and also the dart 20 with the Reher Morrison port program as they seem to flow heaps. The Brodix have the smallest port volume of the 3 heads but seem to flow the most.
Thanks for any help and advice.
If staying conventional, you need at least a 370cc port, 2.350-2.4" valve

Imo if you arent using sr20 for a class rule, use a big spreadport 12 degree/18 degree 11:1 and a 284/304 will get you 1000+ with either head.

I've built plenty of combos that make over 1000pump, Cam it at .800" it will live just fine with the right parts and clearances

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Re: Big HP on pump gas.

Post by englertracing » Sat Jun 23, 2018 12:25 pm

Build a big block ford. :lol:

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Re: Big HP on pump gas.

Post by Frankshaft » Sat Jun 23, 2018 12:33 pm

englertracing wrote:
Sat Jun 23, 2018 12:25 pm
Build a big block ford. :lol:
Not to hijack the guys thread, but I SERIOUSLY considered building a stock cast iron 4v headed 408 for my Camaro. lol. I would imagine you could make a ford fit in a chevy, considering more fox body mustangs have chevy engines in them, a Ford in a chevy should be doable. It takes a pretty good aftermarket head and some effort to make a REAL 700+hp with a sbc, you can do it with factory castings on the 4v Cleveland, and you actually make them smaller, lol.

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Re: Big HP on pump gas.

Post by user-23911 » Sat Jun 23, 2018 6:13 pm

100HP per litre is about where it's at without boost.
With 98 RON.

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Re: Big HP on pump gas.

Post by AA Performance » Sat Jun 23, 2018 11:14 pm

Frankshaft, the brodix 1201 seen to have lots of flow. Have you used them? I was thinking of trying to keep port volume down a bit as to keep throttle response and torque up as much as possible without revving the thing too much. I know its going to have more than he will ever be able to use but some customers are happy as pig in shit if they can shout out bigger numbers than the other guy and it more importantly gives me the opportunity to try something a little different than I normally would, especially when the customer is prepared to go this route and pay the expenses. Engine will probably be a 4.600 bore with a 4.75 stroke and reason of the 10.6 block is to give the engine some rod length and some skirt on the piston with a conventional ring pack for street miles. I'm not a real fan of running a 1.4 or less rod ratio for higher mileage stuff. I like the route that 'apm' went with big cubes but he must have around 1.34 rod stroke ratio and I wonder how the piston would hold up once you start getting it down the track and do some miles. It will be single carb and N/A and no class rules but must fit into a 68 camaro street car with no major chassis mods.

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Re: Big HP on pump gas.

Post by Frankshaft » Sun Jun 24, 2018 11:31 am

AA Performance wrote:
Sat Jun 23, 2018 11:14 pm
Frankshaft, the brodix 1201 seen to have lots of flow. Have you used them? I was thinking of trying to keep port volume down a bit as to keep throttle response and torque up as much as possible without revving the thing too much. I know its going to have more than he will ever be able to use but some customers are happy as pig in shit if they can shout out bigger numbers than the other guy and it more importantly gives me the opportunity to try something a little different than I normally would, especially when the customer is prepared to go this route and pay the expenses. Engine will probably be a 4.600 bore with a 4.75 stroke and reason of the 10.6 block is to give the engine some rod length and some skirt on the piston with a conventional ring pack for street miles. I'm not a real fan of running a 1.4 or less rod ratio for higher mileage stuff. I like the route that 'apm' went with big cubes but he must have around 1.34 rod stroke ratio and I wonder how the piston would hold up once you start getting it down the track and do some miles. It will be single carb and N/A and no class rules but must fit into a 68 camaro street car with no major chassis mods.
Yes, I have used the 1200 series heads. They make power. The 1203 is a good head to start with, its a as cast type head designed to run as is. Cnc chamber, bowl blend, etc. It's 475cc, but that is deceiving. The port is long, the cross section is conservative, an example, a ported Dart 18 degree head that pours 450cc, is a lot bigger in cross section than the 1203 heads, because of the raised runner, there is more port length. But, the 1203's really need to be ported. Use the gasket for their 1204 head, and raise the port to that. It sounds like you need the Big Victor intake. It is much lower, and will fit better under a hood. Will require less cowl. A Profiler 12 degree isn't as good in my opinion, but would work. They are similar though. Only problem with the shallow angle stuff, trying to run pump gas on a big engine, the compression can easily be 14.5-15:1 with a flat top. Now to think of it, a Dart Pro 1 18 degree big chief, with porting would be a good head to start with.

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Re: Big HP on pump gas.

Post by shoedoos » Mon Jun 25, 2018 3:41 am

weld up intake on here if you go the Big Chief route...

https://www.performanceboats.com/parts- ... chief.html

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Re: Big HP on pump gas.

Post by AA Performance » Tue Jun 26, 2018 7:53 pm

Thanks Shoedoos but not for me. Want to keep it under the bonnet as much as possible and that will add a lot more expense to the customer. Can some one tell me what makes a head more suitable for nitrous? Was looking at the brodix 16° for this application as they have good flow numbers were we want them, a cast intake is available and with the relatively small port volume I would think that they would give us some big torque numbers with plenty HP. Why would anyone want 40 - 60cc more port volume for less flow in a 632ci with a max RPM in the high 6000's. Am I missing something?

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Re: Big HP on pump gas.

Post by Frankshaft » Tue Jun 26, 2018 9:03 pm

AA Performance wrote:
Tue Jun 26, 2018 7:53 pm
Thanks Shoedoos but not for me. Want to keep it under the bonnet as much as possible and that will add a lot more expense to the customer. Can some one tell me what makes a head more suitable for nitrous? Was looking at the brodix 16° for this application as they have good flow numbers were we want them, a ca I'mst intake is available and with the relatively small port volume I would think that they would give us some big torque numbers with plenty HP. Why would anyone want 40 - 60cc more port volume for less flow in a 632ci with a max RPM in the high 6000's. Am I missing something?
The difference is the combustion chamber mainly. The sweet 16 is more nitrous friendly, and is their attempt to cover both ends. Generally, the 11 and 12 degree stuff has much smaller, more efficient Chambers that need less timing generally. So, on nitrous, you need to tone down the chamber so to speak. You also take a bunch of timing away. Shallow angle heads can still be softened, to be more nos friendly too. The other thing, that 632 needs a lot of head. Making tq shouldn't even be a consideration, because it will make to much anyhow, for most street cars to deal with. Let it fall where it falls, 850+ ft lbs is plenty. The other thing, like I mentioned above, as the valve angle is reduced, and the ports are raised, they get longer. So a given cross section will have more volume, that's why comparing volume on any head isn't usually accurate. Especially on the spread port heads. They vary a lot between brands and depending on which head. For example, the Dart big chief 18 degree heads have a much shorter port than say the brodix pb1203 12 degree heads. The port volume is about a 50cc swing at a given Cross section. That's why you really can't use port volume on that style of head to compare them.

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Re: Big HP on pump gas.

Post by Warp Speed » Tue Jun 26, 2018 10:39 pm

A 10.2 598 with some Slick Rick SR20s would do it EASY! :wink:

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