GTP Cool Wall: Dodge Neon SRT-4

[Famine]

Some guys added a Turbo and tuned it slightly and got it to hit 221mph. I don't know of another FWD that can do that.

The SRT-4 already has a turbo. And "tuned it slightly" requires at least another gearbox, since the existing one won't run that far unless the car has 22" wheels...

Not that it's relevant, since modified cars != production cars.

BTW, you're right, the SRT4 is the second fastest stock FWD car. The first is the Vauxhaul Vectra VXR...'cause it has the GTO engine in it.

The Vectra VXR doesn't have a GTO engine. It's a 2.8 litre turbo V6. But yes, it's a FWD car faster and more powerful than the SRT-4 (though not quicker) - and they did an estate/wagon version that was also faster and more powerful than the SRT-4...

There are others too.

 

[Enigma]

Some guys added a Turbo and tuned it slightly and got it to hit 221mph. I don't know of another FWD that can do that.

Deja vu ?

There was a guy in Evo magazine with a 90's Audi coupe running 1800 bhp that would out accelerate a veyron, whats your point ?

 

[Tornado]

What he is saying is actually a different point from the one made before, so your previous comment doesn't apply.

BTW, you're right, the SRT4 is the second fastest stock FWD car.

At the time, a Cobalt SS could beat it, depending on the track. The Mazdaspeed 3 was the same way. The more recent Cobalt SS would destroy it any time, anywhere. To say nothing of the more recent Focus RS or the various Renaults.

 

[Enigma]

What he is saying is actually a different point from the one made before, so your previous comment doesn't apply.

They were along the same lines, talking about what these cars can do modified, fair enough the second person didnt make an exact comparison against other standard cars.

Also, to say that someone changed the turbo and tuned it slightly (remap/exhaust ?) to hit 221mph is a massive understatement, I would imagine pretty much every engine internal would have been changed.

 

[Tornado]

No, he was saying that he doesn't know of any other FWD car that can do 221 when only slightly modified. He was comparing modified SRT-4s to other modified cars, saying that the SRT-4 could be made faster for less money then most other FWD cars of similar performance. Which is actually true.


The validity of his actual statement is still in question, because the transmission tops out at 156; but the stock engine internals are good for something like 350-400HP, I believe. And Chrysler sold kits that brought the engine up to near that.

 

[Enigma]

He didnt mention anything about money.

I will say it again, a new turbo and some slight modifications are not going to make this car do 221mph.

 

[Tornado]

He didnt mention anything about money.

Then substitute "less money" for "less effort," which is more in line with his original statement. It is true either way.

I will say it again, a new turbo and some slight modifications are not going to make this car do 221mph.

SRT-4 is good for around 450 on stock internals. Yes, by which I mean exactly "a new turbo" in regard to level of modifications. You can also do up to 500, but you would then need to replace the pistons every 15-20k or so.
You would still need a different transmission, but it doesn't seem too far-fetched to me.

 

[Enigma]

Then substitute "less money" for "less effort," which is more in line with his original statement. It is true either way.


SRT-4 is good for around 450 on stock internals. Yes, by which I mean exactly "a new turbo" in regard to level of modifications. You can also do up to 500, but you would then need to replace the pistons every 15-20k or so.
You would still need a different transmission, but it doesn't seem too far-fetched to me.

I suggest you watch the fifth gear video about 200mph cars.

Fensport Toyota Corolla
700 bhp, £35,000 worth of parts, 3 years to develop = 200.4 mph
Destroyed its gearbox during a top speed run.

Ford Sierra Sapphire Cosworth
850 bhp, £43,000 spent, 6 years to develop= 206.1 mph

Does it seem far fetched to you yet ?

If I knew how to I would give you a link but I'm dumb with computors, just google it.

 

[Famine]

The numbers suggest an SRT-4 would require 695hp at the crank (I can show my working if desired) to reach 221mph, plus the appropriate gearing to do so.

This would lend itself to the notion that "adding a turbo" and "tuning it slightly" would be understating it somewhat.

 

[Tornado]

I can show my working if desired

Yes. I believe you, but I'm curious as to the speculations required.

 

[Famine]

Yes. I believe you, but I'm curious as to the speculations required.

You need a couple of assumptions.

First is a uniformity of the Earth's gravitational field (it's not, but it's close enough not to throw the results out by more than a third decimal place) to account for the car's rolling resistance which is notionally the same at any speed less any upforce created at speed by the change in air pressure around the vehicle - or with any downforce added by wings. An F1 car may weigh the equivalent of a 1000lb mass at rest, but at 120mph it's producing its own weight again in downforce.

Second is a unformity of air density. This has more significant changes associated with it - denser air is harder to push through than thinner air - but they're handily balanced out by the workings of the internal combustion engine - denser air gives more power than thinner air.

Third is an approximation of drivetrain efficiency. This is commonly out by a bit, but the assumptions are the same most rolling roads give - 15% losses for FWD and rear/mid-mount RWD, 17.5% losses for front and front-mid mount RWD, 25% for 4WD - but really it can be dispensed with altogether since crank power is wholly irrelevant to anything.

At that point all you need is the car's mass (plus or minus speed-associated weight), the drag coefficient, the frontal area (the area of the car presented to the air - think of squishing it perfectly between two rams front and rear. The frontal area is the area of the 2Ded car) and, most important of all, the speed.

Now, for most cars we don't have a frontal area - it's not very commonly measured - but we can arrive at a "just about" frontal area if one isn't available. Multiply the vehicle's width by the vehicle's height less four and a half inches. Why less 4.5"? Space under the car isn't frontal area - it provides no wind resistance at all, because it's space. Most cars also taper from the shoulder to the roofline. But then we also have the tyres and the wing mirrors presenting themselves to the air. I prefer using a frontal area - or a CdA - where available, but this gives bloody good approximations.

Now the maths.

Rolling Resistance = Vehicle weight (lb) x 0.0135
Air Resistance = Cd x Frontal Area (sq. ft) x 0.00256 x Speed (mph) x Speed (mph)
Total Resistance = Rolling Resistance + Air Resistance

Wheel Power Required at given speed = Total Resistance x Speed (mph)/375
(Crank Power Required = Wheel Power/Drivetrain Loss [0.85, 0.825, 0.75])

*0.0135 is the first assumption
*0.00256 is the second assumption

So for the SRT-4 to hit 221mph:

Rolling Resistance = 2900lb x 0.0135 = 39.15lb
Air Resistance = 0.35 x 22.67 x 0.00256 x 221 x 221 = 992.26lb
Total Resistance = 39.15 + 992.26 = 1031.41lb
Wheel Power Required at 221mph = 1031.41 x 221/375 = 608whp
(Crank Power Required = 715hp)

I'd used a different width value earlier, due to a little lack of clarity about whether wing mirrors were included in the overall width. This new figure ought to be closer to reality - though again, crank power is wholly irrelevant, so working with the smaller, wheel power number is better.

 

[Tornado]

Ohh. 15%. That would explain it.

I'd actually seen you use that stuff before (I think it was about the story of the Sonata caught doing 147), and I was trying to apply that.

 

[Famine]

It's what most rolling roads use. It's horribly inaccurate - which is why most people who care don't bother with it and stick with wheel power. It is, after all, that the does all the moving.

 

[niky]

Fensport Toyota Corolla
700 bhp, £35,000 worth of parts, 3 years to develop = 200.4 mph
Destroyed its gearbox during a top speed run.

Ford Sierra Sapphire Cosworth
850 bhp, £43,000 spent, 6 years to develop= 206.1 mph

You do know that UK shops charge an arm and a leg for parts and labor? That 35k worth of parts, if made in the US, would probably equal just $40-$45k

I'd like to point out that throwing 35k worth of parts into a Corolla includes replacing the naturally aspirated mill with a turbo-mill and an entire drivetrain from a Celica GT4, since you could spend 35k on the 1.8 liter engine alone and still not get anywhere close to 700 hp. And duh, it destroyed its gearbox, because the gearbox wasn't (re)built for the power and wasn't geared for any more than that.

Oh. And since it uses an entire GT4 drivetrain, it's not FWD.

No, he was saying that he doesn't know of any other FWD car that can do 221 when only slightly modified. He was comparing modified SRT-4s to other modified cars, saying that the SRT-4 could be made faster for less money then most other FWD cars of similar performance. Which is actually true.


The validity of his actual statement is still in question, because the transmission tops out at 156; but the stock engine internals are good for something like 350-400HP, I believe. And Chrysler sold kits that brought the engine up to near that.

He makes the claim because it's entered in under "production" records at Bonneville.

Which means that it has to use the same basic engine (never mind what's inside or what modifications have been done to it) and same body, with no big aero. And it takes around 700 hp to do that.

Chrysler claims it's the same transmission. What they neglect to mention is that the internals are different, too... which they have to be to even handle the power.

It's possible you could get a Mazdaspeed to do that, but you'd probably have to sleeve the block and lower the compression. The SRT4's advantage is that it's one of the last iron-block turbocharged cars, and it had an incredibly low compression ratio (8.1). It may be possible to get 700 hp out of the bottom end: some of the better Japanese 2.0s (20% smaller) can make 400-500 whp+ on the stock bottom end... and they have 8.5 compression, typically. You'd need months of fiddly tuning and a few broken engines to arrive at this result. You won't have any custom parts on the bill, but the dyno time alone should run into five figures (assuming about $100 an hour), and, if they break anything on the dyno, you're adding another few thousand to that.

 

[Famine]

And duh, it destroyed its gearbox, because

It's a GT4 gearbox.

 

[Eric.]

Whether or not an SRT4 is cool or not has come down to arguing about 200mph FWD cars?

 

[astrosdude91]

130+ comments will do that to a thread.

 

[Famine]

Whether or not an SRT4 is cool or not has come down to arguing about 200mph FWD cars?

Looks like an emergent discussion between three people who've already voted long ago to me, rather than deciding whether it's cool or not through arguing.

 

[Enigma]

And duh, it destroyed its gearbox, because the gearbox wasn't (re)built for the power and wasn't geared for any more than that.

Oh. And since it uses an entire GT4 drivetrain, it's not FWD.



He makes the claim because it's entered in under "production" records at Bonneville.

Which means that it has to use the same basic engine (never mind what's inside or what modifications have been done to it) and same body, with no big aero. And it takes around 700 hp to do that.

Chrysler claims it's the same transmission. What they neglect to mention is that the internals are different, too... which they have to be to even handle the power.

I could be wrong but I thought if they were running that kind of power they would have modified the gearbox, is a standard GT4 box geared for 200 mph?

Fair point these cars are not FWD, I was just trying to give Tornado an insight into whats involved in making your average turbocharged 4 cylinder saloon/hatchback do 200mph.

You seem to be in agreement with me that its not just a case of changing the turbo.

 

[riivaaja]

It's interesting to see all the stereotypes about this car as I read through this thread. There are so many things to comment on, I don't even know where to start.

This car is my daily driver. The interior is not terrible or that uncomfortable, even driving 1200 miles across the country. Sure it creaks inside but so what. The power is awesome for passing on the highway/freeway and I imagine it would be awesome on a track after driving an hour and a half, back and forth, over a steep mountain pass on weekly basis. I've never raced off a light before, bullied other cars, or wore sports wear to dinner. The car sits on the road and not on top of the world. It has a much meaner, wider stance and much rougher ride than a regular Neon, so even though its based on that platform, its looks are still a tastefully different. Its reliability has yet to fail me after driving 13,000 miles in it (the odometer reading 60,000 when purchased) with the only modifications being an aftermarket exhaust and Mopar blow off valve that I bought the car with and MSD coil pack I installed myself.

Cool is obviously relative to the perspective, and while I don't have the love for my car like I did with my first vehicle, it is far more satisfying to drive.