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Discussion Starter #1
Long story short, as of Tuesday, I have another 08 Roush 427R. It’s a torch red coupe, 57K miles. Decided not to build my blue one and bought another. I originally wanted a red one when I was looking for one, but the deal on the blue was too good to pass up. The cars are fun enough at their power level, and two are better than one. I don’t have many photos of it but I’ll get them later. Little about the car, has the roush 4 piston big brakes up front but it didn’t come from the factory with them. Has unknown off-road X, probably BBK, and had flowmasters. As of yesterday it has the original roush mufflers off the blue one currently. Sounds so much better. Car is #235.

IMG_4491.jpg



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That's pretty cool! Even the floor mats say 427R!
It looks like that car has a few more horsepower than 427. Did they put each car on a dyno? Or did they have a bunch of those placards made up and put on randomly.... "We'll call this one 432 hp.This one looks like she'll put down about 434 hp. This one is a damned freak, 438 hp, etc".
 

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Discussion Starter #7
That's pretty cool! Even the floor mats say 427R!
It looks like that car has a few more horsepower than 427. Did they put each car on a dyno? Or did they have a bunch of those placards made up and put on randomly.... "We'll call this one 432 hp.This one looks like she'll put down about 434 hp. This one is a damned freak, 438 hp, etc".
Disregarding the sarcasm, the 427R package’s first year of production was 427/391. Second year and onward they tuned it to 435/400.


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I wasn't being sarcastic.... That was a legitimate question and display of my lack of knowledge about that particular car.

Here is another:
Do dyno results typically confirm that 435 hp number?
More or less?
 

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Discussion Starter #9
It’s crank figures. Generally they dyno at 370-375 at the tires. But a simple tune will get them up to 400. VMP claims with a 2.49 pulley and CAI it’s almost 430rwhp.


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I like them a lot. (Duh)
The goal is for the GT and the Mach to be close to the twins in performance. What I want to do to the GT can at the least be at 350 without heads. With heads maybe 365? I haven’t really seen anyone with the set up I want to use. Closest was everything with stock heads at 348-353rwhp. The Mach will just be headers and cams and maybe a throttle body. I don’t need 500+rwhp, I enjoy the hell out of my boosted 3V’s at under 400. Though I’m not a fan of that tiny blower, I’ll keep it on them. It’s fine for what I use the cars for. Kinda pathetic they’d use a six banger blower on a V8 but what do I know.


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Until recently, the manufacturers seemed content installing superchargers that are just big enough to achieve the desired horsepower, and not much more.
With a pulley, it sounds like it is getting pretty close to what many consider as being the safe horsepower limit for the 4.6 rotating assembly anyway. Although, I think that there are a lot of 4.6 cars in the mid 500's reporting no problems. Probably, a good tune, and the luck of the draw whether a rod breaks or not.
Nobody needs a 500+ whp car. I still would like to have a car, or truck, that has slightly more power than is actually usable though.... Whatever that number may be. Just for grins every once in a while.

Anyway, I think that the supercharged 3V's are becoming a good bargain for a factory built hot rod.
 

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Discussion Starter #13
The biggest issue is the blower. It’s an M90. I have a boost gauge in the blue one and it’s making 5lbs. I might be lucky to get 9-10lbs max. That’s spinning that blower hard, and it overheats quickly. It’s a 3 blade rotor system. My old SSEI Bonneville M90 made 9lbs with the factory pulley which was substantially larger than the one on the Roush M90. VMP does make a 1.7L TVS blower swap that’s pretty good. I saw someone make 500rwhp on it but stopped going further due to concerns of the internals. I do have a spare M90 head unit I bought from Roush when they were cleaning out their factory. I thought about sending it to Steg to have it ported but I still don’t know if I’ll do that. Nitrous is another alternative, but I don’t like the fact that it will run out. Anyway the main focus is to fix some issues on the red one and do a few more mods to make her better. Engine wise I’m not really going to do anything, but some visual and suspension mods are planned.


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IMG_4492.jpg

Took them to a car show over the week end. Hopefully the red one will get some different shoes tomorrow or next week. Other thing it’ll get is a shorty antenna. I can’t stand the stock antenna anymore.


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Beautiful Cars. I have the white with blue strip and blue Roush Seats. I will never sell mine due to how rare these cars are. Be careful how much you try to get out of these stock 4.6s. even at 500 HP it is risky with the internals. I have the smaller pully on mine along with the Roush CAI. On a perfect day I may be about 475 HP. Roush told me that is all that they would recommend on the stock engine. Sure there are a couple in the local club who are pushing more but they are rolling the dice. I have had mine on the track and what I have is plenty. I have the Roush Track Pak Gauges that were offered back in the day and I can only get about 7 PSI. One of the reasons for this even with the smaller pully is that the 4.6 is very efficient on the intake side so it is hard to build a lot of pressure with the Roots blower.

On these cars I would recommend installing ductwork on the driver side brake duct and route directly into the cold air box. These cars get hot under the hood and anything you can do to cool that air will help. I have done this on mine and have noticed a difference in inlet air temp. While not a big difference, every little bit helps. This is not an expensive mod. Without this mod the CAI is not really a CAI as it is just sucking hot engine compartment air.

A lot of fun to drive just the way they are.
 

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Discussion Starter #16
Beautiful Cars. I have the white with blue strip and blue Roush Seats. I will never sell mine due to how rare these cars are. Be careful how much you try to get out of these stock 4.6s. even at 500 HP it is risky with the internals. I have the smaller pully on mine along with the Roush CAI. On a perfect day I may be about 475 HP. Roush told me that is all that they would recommend on the stock engine. Sure there are a couple in the local club who are pushing more but they are rolling the dice. I have had mine on the track and what I have is plenty. I have the Roush Track Pak Gauges that were offered back in the day and I can only get about 7 PSI. One of the reasons for this even with the smaller pully is that the 4.6 is very efficient on the intake side so it is hard to build a lot of pressure with the Roots blower.

On these cars I would recommend installing ductwork on the driver side brake duct and route directly into the cold air box. These cars get hot under the hood and anything you can do to cool that air will help. I have done this on mine and have noticed a difference in inlet air temp. While not a big difference, every little bit helps. This is not an expensive mod. Without this mod the CAI is not really a CAI as it is just sucking hot engine compartment air.

A lot of fun to drive just the way they are.
See post 13, as I state what the issue is. I have a NOS P-51 shortblock, if I ever wanted more power. Biggest thing is if the M90 stays on the car is keeping it cool, which is a challenge. As I said I have another M90 head unit that I debated on getting ported to possibly improve the efficiency of the blower. But I’m still debating it, I don’t see real value in investing to improve the supercharger. It’s too close to it’s limits already, and 2.3L TVS is just so much better.
If I were to put cooling ducts on the car they would be for the brakes.


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Sorry, Missed the detail about the P-51 block. In that case you are completely correct. The way yo go would be to go to the bigger blower.
 

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Sorry, Missed the detail about the P-51 block. In that case you are completely correct. The way yo go would be to go to the bigger blower.
I’m sorry I didn’t speak clearly. I have the shortblock but it isn’t in anything. And I’m not sure I’ll use it now. The block, itself, is worth some money and it’s new. Roush clean out their factory a few years ago and I bought several 3V oriented parts. One was their last NOS P-51 engine.


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