4.6L Build Up Questions...

tjm73 · Nov 9, 2005

I am curious about what realisticly could be expected from a dedicated naturally aspirated 4.6 build up in regards to power. I read an article once where they got around 400 hp at the crank. I thought that was pretty good for a 4.6L 281 inch engine. It's 1.42 hp per cubic inch, about 87 hp per litre.

The engine would be simple and built as follows...

C&L MAF & Inlet Tube
70mm TB
C&L Inlet Elbow
Stock PI Intake
Ported PI Heads
The Smallest Comp Cams (stage 1 type specs?)
10:1 Compression Forged Pistons on H-Beam Rods
Computer Tuned
FRPP Headers
Catalytic X-Pipe
NO Underdrive Pulleys
NO Timing Adjuster (timing would be computer controlled & part of the tune)

Basically concentrate on get it in and get it out.

Emissions inspections are mandatory so no cats is no option. Big cams are not an option ether. A custom set of cams would be a distinct possibility.

98stangv8 · Nov 10, 2005

tjm73 said:
I am curious about what realisticly could be expected from a dedicated naturally aspirated 4.6 build up in regards to power. I read an article once where they got around 400 hp at the crank. I thought that was pretty good for a 4.6L 281 inch engine. It's 1.42 hp per cubic inch, about 87 hp per litre.

The engine would be simple and built as follows...

C&L MAF & Inlet Tube
70mm TB
C&L Inlet Elbow
Stock PI Intake
Ported PI Heads
The Smallest Comp Cams (stage 1 type specs?)
10:1 Compression Forged Pistons on H-Beam Rods
Computer Tuned
FRPP Headers
Catalytic X-Pipe
NO Underdrive Pulleys
NO Timing Adjuster (timing would be computer controlled & part of the tune)

Basically concentrate on get it in and get it out.

Emissions inspections are mandatory so no cats is no option. Big cams are not an option ether. A custom set of cams would be a distinct possibility.

with no pulleys and regular mid pipe...I would say around 320 at the crank...check my mods and my numbers, and you may get a "ballpark"

mattkimsey · Nov 10, 2005

If that's the same article I read, they only had 1 accessory hooked up.

mattkimsey · Nov 10, 2005

I agree with 98stangv8, ~320hp would probably be pretty close with the stock intake, stage 1 cams, cats, no pullies, and shorty headers(not sure if those are longtubes)

Built98GT · Nov 10, 2005

I might be a little off here but i think you would be in the ballpark of about anywhere from 250 to 270 to the wheels.<-Someone correct me if im way off.If i was u i would either go with like some vt stage 2 cams or the comp xe270's i dont think they would be to big of a cam for you since you said your not wanting big cams.

MatthewP · Nov 11, 2005

If you are going to run the XE262AH cams, you might as well stick with the stock pistons and rods. Also, don't waste you money on the "shorty" headers. Bassani's "mid length" headers are more like what you would normally call shorties, but are a lot easier to install than real long tubes.

I've tested this kind of combination at about 260 RWHP on a Mustang MD-600 dyno, and estimate that to be about 345 HP SAE Net (Flywheel).

-Matthew

reddrgn01gt · Nov 11, 2005

If you are going to spend all of that money why not just get a supercharger?

tjm73 · Nov 11, 2005

reddrgn01gt said:
If you are going to spend all of that money why not just get a supercharger?

I preffer naturally aspirated engines. A powerful N/A engine is more impressive to me than a boosted or juiced engine. I like superchargers and they are cool as hell, but I don't want one.

Second, economics. I would be starting with a high mileage engine, so either way it needs a rebuild. A supercharger will add a minimum of $3500 on top of a freshening.

reddrgn01gt · Nov 11, 2005

tjm73 said:
I preffer naturally aspirated engines. A powerful N/A engine is more impressive to me than a boosted or juiced engine. I like superchargers and they are cool as hell, but I don't want one.

Second, economics. I would be starting with a high mileage engine, so either way it needs a rebuild. A supercharger will add a minimum of $3500 on top of a freshening.

I completely agree with you about N/A engines. I didn't realize your set of circumstances. I am looking to do further upgrades in the spring and found in my case a supercharger would be way cheaper and give me more power.

tjm73 · Nov 11, 2005

reddrgn01gt said:
I completely agree with you about N/A engines. I didn't realize your set of circumstances. I am looking to do further upgrades in the spring and found in my case a supercharger would be way cheaper and give me more power.

Yeah my '98 is nearly paid for (I bought it used about 2 years ago) and I absolutly love the car. And I want to boost the power in a big way, but it has 83,000 on it right now (zero rust) and after it's paid off I am thinking about bumping the power up some.

If I could get 1.25 hp /cubic inch I'd be very happy. That's about 350 hp at the crank.

What I'd really like to do is swap ina 5.4, but swap headers and intakes are not available as of yet. Not that I know of at least.

Drag_on · Nov 14, 2005

My .02 is to do something different with the compression, either higher or lower. With your current plans, there is no need to change the bottom end right now unless you get more power out of it. I'd say go 11:1 or slightly higher if you want to stay N/A. I recently heard of a car making about 350 rwhp N/A on 12:1 with most bolt ons and race gas, but the guy said that was just an estimate (since they are a mod motor shop and work on stangs only it is prolly a decent estimate).

--SHM sells a 400hp N/A (crank) that comes with a dyno sheet. If they can do it then you can.

--VT engines should be able to get you well over 300 to the wheels with the right set up

--A good tune can make all the difference.

ADRENLN · Nov 15, 2005

i have about 325 (crank) right now. 290 to the wheels. i have a very streetable car. i have cats, and cams are very unaggressive. i do have the long tubes. dont think my set up would pass emmissions but it is very close.

the set up i have cost me a ton of money. think about a blower, but your right you would have the get forged internals to run it so it would be more expensive.

Drag_on · Nov 15, 2005

MatthewP said:
If you are going to run the XE262AH cams, you might as well stick with the stock pistons and rods. Also, don't waste you money on the "shorty" headers. Bassani's "mid length" headers are more like what you would normally call shorties, but are a lot easier to install than real long tubes.

I've tested this kind of combination at about 260 RWHP on a Mustang MD-600 dyno, and estimate that to be about 345 HP SAE Net (Flywheel).

-Matthew

Was that without ported heads and no other bolt ons besides "mid length" headers?

MatthewP · Nov 16, 2005

Drag_on said:
Was that without ported heads and no other bolt ons besides "mid length" headers?

That car had all of the common bolt ons, long tube headers, and a "flap wheel" port job on the heads.

I recently did an install of the Bassani "Mid Length" headers on my own 02 GT, and they are a lot easier to put in than the long tubes, but unlike the "shorty" headers for the 2V mod motor cars, they are real headers. The "mid length" headers are what most 5.0 guys would normally call shorties, whereas the 2v "shorty" headers are basically a tubular version of the log manifolds. My 02 is turning out pretty nice, but I am not ready to announce the final results of that project just yet.

I would say that with a similar parts menu you can build a reliable N/A 2V car that will run right alongside a 5.0 car.

-Matthew

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