most reliable way to get a 330-350HP motor

Bareass
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most reliable way to get a 330-350HP motor

Post by Bareass » Fri Jun 07, 2013 5:11 am

Hey all,
I'm currently driving a 84 GTV6 with a 3.0L 12V. its a lot of fun, and its pretty quick, but the 24V i have sitting in the corner would be much better!

my goal is to be between 350 and 400 hp at the motor. That should easily be handeled by the transaxle.

what is the easiest way to do this?


Things i have been considering is supercharging, but i'm not sure what is involved, and boring to a 3.5L. I have a machine shop that can bore the block for me, for little to no cost.
I want to stay away from turbo charging... i don't like the way it shapes the sound

thanks!
Last edited by Bareass on Wed Jun 12, 2013 5:27 am, edited 1 time in total.
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Re: most reliable way to get a 350-400HP motor

Post by Duk » Fri Jun 07, 2013 8:49 pm

Bareass wrote: my goal is to be between 350 and 400 hp at the motor. That should easily be handeled by the transaxle.
Haha! I think you should be held to that. :wink:

In theory, torque is the big smasher of things!
If you had a decent turbo diesel engine that made 400hp, it would be doing so only because it made about 500,000 lb/ft (give or take a few) of torque, because diesel engines don't rev well.
But a normally aspirated 3.5 litre engine would need to be revving half way to the moon (8000ish RPM) to make that kind of power and would need less torque to do so.
Bareass wrote:what is the easiest way to do this?


Things i have been considering is supercharging, but i'm not sure what is involved, and boring to a 3.5L. I have a machine shop that can bore the block for me, for little to no cost.
I want to stay away from turbo charging... i don't like the way it shapes the sound

thanks!
A good supercharger set up can do this and do it quite easily.
Your choices are either a centrifugal supercharger that will give a very progressive boost curve and so a very progressive torque curve. I would expect that a centrifugal SC would be the nicest to the TA. Vortech are an obvious name, but I think that Rotrex would be making better superchargers.
However, a good positive displacement SC will give MUCH more low RPM boost and so the engine can make MUCH more low RPM torque!
At bare minimum, a good Eaton MP90 would move enough air to do the job, but a newer Eaton TVS 1320 would be a better choice.
There are also the twin screw superchargers from the likes of Whipple, Lysholm and Sprintex.

Any ways, there is a guy here in Aus that has a Vortech blown 3 litre 12 valve that is making around the 500hp mark: http://www.alfabb.com/bb/forums/engine- ... 3-0sc.html

As is always the case, you must have good intercooling, excellent control of your engine, a fuel system to keep up with the air flow, engine temperatures under control, a well flowing set of extractors and a exhaust (think 3" main system, minimum) and when pushing these sorts of numbers, a built engine (typically lower compression pistons (forged) to handle the combustion pressures (not that it will be massive) and maybe some stronger conrods).

If you went the NA route, you could probably get 350hp with a 3.5 litre, but given that there is no variable valve timing with these engines, you'd inevitable loose low RPM torque to make higher RPM torque. If it's purely a track car, no big deal. But if it's a road car, the fatter torque curve of the even the centrifugal SC set up, would make the car easier and faster to drive, and typically give better 'day to day' fuel economy.
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Re: most reliable way to get a 350-400HP motor

Post by Bareass » Mon Jun 10, 2013 3:42 am

i always thought the limit of the transaxle was around 350 whp. is this not the case?
would a goal of say 330 hp at the crank be more of a realistic number for a road going engine?
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Re: most reliable way to get a 350-400HP motor

Post by Greg Gordon » Tue Jun 11, 2013 3:34 pm

I firmly believe that more than 350whp is going to result in a very short transaxle life. What's the most reliable way to get 350-400hp? It's forced induction, either supercharger or turbocharger. Reaching that level of power with a normally aspirated Alfa V6 is very difficult.

It's no secret I favor the supercharger, although I have done both and like turbos too.

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Re: most reliable way to get a 330-350HP motor

Post by Bareass » Wed Jun 12, 2013 5:28 am

title changed to reflect a more realistic goal.
any reason why 330-350hp at the crank should be difficult to obtain?

will to take any and all sugestions. I have a 3.0 12v with sperry heads, S cams, and a pandora's box, and a RWD converted 3.0 24v with GTA runners, GTA stage 2 cams, and a gotech. i have access to a boring machine, and machine shop.
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Re: most reliable way to get a 330-350HP motor

Post by 75evo » Wed Jun 12, 2013 8:32 am

You can get 300 bhp from a stock GTA engine. Marc has done it on his SZ. Just a new aftermarket ECU. Check out his car in the intro section.

So to get 350 @ crank from a 3.5 isn't such a big deal. But things like 10mm cams, 11:1 compression comes to mind. Nothing less. Although your torque won't be that great for a 3.5 since the crank's stroke is very short.

This is one reason I went with a 3.2 instead of sticking with a 3.0. That and I get to use all OEM head gasket which looks to be one of the main problems of the big bore conversion. Getting it to seal and not leak after a while. But it looks like a few people have successfully done it. Kevin, JJ, and a few others are experts at this stuff.
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Re: most reliable way to get a 330-350HP motor

Post by Bareass » Thu Jun 13, 2013 8:14 am

so what about supercharging a 3.0?
would that give me better torque numbers?
i would have to build the engine with a lower compression ratio, what numbers are people using, and how is the power across the band?
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Re: most reliable way to get a 330-350HP motor

Post by Greg Gordon » Thu Jun 13, 2013 4:12 pm

It's no contest, the supercharged engine will kill the n/a engine. Here is an example: https://www.youtube.com/watch?v=0MFKMYN6xZw

The supercharged car here is a 3.0 with a 2.5 crank giving 2.7 liters and is a relatively low budget affair. It easily out accelerates everything else on the track including the hot 24 valvers.

The owner of the car won the race series, not just this race.

I have one customer here in Tulsa with a supercharged 2.5, 8.5:1 pistons, "S" cams, a supercharger intercooler, and SDS. He has run the 1/4 mile in the high 12s at Tulsa's dragstrip. It's really mid 13 second car, but his best run is in the 12s.

I love hot N/A engines as much as the next guy, but the power just doesn't compare.

There is NO series in racing where normally aspirated engines compete successfully with forced induction engines without serious rule adjustments to level the playing field. Usually these are in the form of higher weight or a lot less displacement.

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Re: most reliable way to get a 330-350HP motor

Post by Mats » Fri Jun 14, 2013 12:18 am

GrpA had a ratio of 1.7 for turbo engines, says a lot.

Now, you picked the race where Hans did the best start EVER, usually the difference is not that crazy. 8)
Note that the 75 that follows him around like it's glued to the back of Hans car is Niclas Rosengrens 12v 3.0 with probably less budget. Very nicely finished engine with a number of tweaks but still all done in Niclas garage. :)
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Re: most reliable way to get a 330-350HP motor

Post by Greg Gordon » Fri Jun 14, 2013 3:11 am

Hey Mats, I was not making a case for supercharging vs turbocharging, I am making a case for forced induction vs normally aspirated. The limit of 1.7 liters for turbo cars makes my point exactly.

Mats, we all know you are a forced induction guy. Don't even try to say you are going to build a NA motor to try and win :)

I picked that video because it's late in the season and Han's car was further developed, but even in it's first outings it was a killer down the straights.


Niclas' car is certainly fast and competitive around the course, but Han's pulls away from it easily on the straights, even when exiting the corners at a lower speed.
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Re: most reliable way to get a 330-350HP motor

Post by Bareass » Fri Jun 14, 2013 4:24 am

so if i were to rebuild my 24V, i have my choices of a few different options.

1) pull apart the bottom end, replace bearings, rings and seals, and keep it 3L

2) pull apart the bottom end, replace bearings, rings and seals, and custom pistions, and Supercharge the 3L

3) pull apart the bottom end, replace bearings, rings and seals, replace the crank, con rods and pistions, and build a 3.2L

4) pull apart the bottom end, replace bearings, rings and seals, replace the crank, con rods, and install custom pistons and build a supercharged 3.2L

4) pull apart the bottom and top end, bore the block, replace pistons, rings, seals, bearings, rebuild the top end, and get custom gaskets, and build a 3.5L


which would you choose?
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Re: most reliable way to get a 330-350HP motor

Post by Giuliettaevo2 » Fri Jun 14, 2013 2:41 pm

5. pull apart the bottom end, replace 3.0 crank with 2.5 one and new rings, bearings and seals. You end up with 2.8 with about 7.7:1 compression... Big single turbo on it and you can enjoy 350 bhp easy. :)

Pistons and rods are nice way's to spend money on but the most important factor in your engine build is the managementsystem and the guy tuning it... :wink:
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Re: most reliable way to get a 330-350HP motor

Post by kevin » Fri Jun 14, 2013 3:16 pm

Supercharge the 12v and save yourself lots of time and keep all that heat out the bonnet . Big Power and reliability come with big budget .
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Re: most reliable way to get a 330-350HP motor

Post by Greg Gordon » Fri Jun 14, 2013 8:25 pm

It's important to realize that even a forced induction 12 valve 2.5 can easily make enough power to break the transaxle, so the 24 valver only offers increases you can't use anyway. At least that's the way I see it.

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Re: most reliable way to get a 330-350HP motor

Post by 75evo » Sat Jun 15, 2013 12:45 am

Bareass,

Don't forget to ask yourself do you simply want to fast or want to fast through a certain way? I like the sound of NA cars.

Listen to Alexis walter's 3.0 12V. 7800rpm of pure Alfa goodness:
https://www.youtube.com/watch?v=I7M7PfYBjBE

Although you do have to admit the supercharged Alfas are hella mean sounding!!!!
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