Over 500 HP with a VG30, why go with a SR?

[Byron510]

You people are starting to make me feel bad for having a VG in my car. I am starting to think like i should apologize for it:(

Hell no - don't do that - no apologies necessary.

I love my I4 motors, and I've never gone another route. But I've also been in some VG510's - and they are fun!

Besides that, Denis' VG wagon here made the best screaming sounds on dyno day out of all the cars, and there were some very well-tuned 510 machines there that day.

So, no apology needed.

I think the point that people are discussing here is that by multiplying atmosphere, you automatically multiply torque. And with the technology ever changing in the world of supercharging, it'll only get better. I drove a brand new Fusion rental car a couple months back - 2L car developing 240 HP with virtually no lag and still gets phenomenal mileage and meets all current emissions standards. Now that is impressive for a power plant.

Byron

[bertvorgon]

No, no..it's ok...this conversation drifted to being careful with ones wish for insane hp, and some of the pitfalls that can produce....

[Byron510]

No, no..it's ok...this conversation drifted to being careful with ones wish for insane hp, and some of the pitfalls that can produce....

Precisely, because those who are "putting down 500 HP daily" are actually few and far between (and most are full of crap) - and magazine HP doesn't count! Magazine HP is right up there with the guy who puts in 116 on the dyno and fudges numbers to get some once off insane HP reading (which isn't repeatable nor could that engine survive at that output for more than a second or two). That's still nearly magazine HP.

I give credence to a flat torque curve though. I once drove a friend’s Gen III RX7 on a small oval track. The car at the time dyno'd near 500 HP and I can attest that once that turbo did spool (bigger single turbo conversion), the thing was near undrivable. Likely, well actually, the most insane car I've ever got behind the wheel of. It's now a 3 rotor, and produced at last count near 700 HP....I told him to not even offer, I'm not interesting. I choose life!


But I also come from a good old V8 hot rod heritage. My father builds and drives lead sleds and I've been around and behind the wheel of many a 300+ HP pony car - never owned one, but liked to drive them. So I too can appreciate the flat torque curve of a warmed over classic V8 that will break the rear end loose just off idle without a clutch drop.

Without any hatin’ it’s good conversation and it really boils down to preference. And I still run my L series

[Ash510]

I have an sr20 with an honest 220 rwhp, and it is a ton of fun. But I would like some more please the bottom line here is what is usable and I would have to agree with Keith and Byron. you only need around 300 max hp before the car is going to be unusable on the street.
now at the track that might be a different story.

but in the end do what you want not what others tell you to do. just my thoughts

Aron

[icehouse]

I still dream of 500 hp haha Even though I normally daily drive the Sunny I got from Rich which is rated at 68hp or my L20 powered 510. I'm just way to cheap to build a 500 hp car. I did help Frank who is always shooting for 500 hp put his engine back together countless times. I don't know the numbers at 16lbs of boost but at 6lbs it dynoed 227whp and it felt week compared to the 16lbs. Getting on the freeway it was burning out all the way through 3rd gear and beyond if you want. My guess would be somewhere around 300whp. The whole time all I can do is wonder, "if this is 300 man I want to drive 500!"

[bertvorgon]

16 lbs boost in anything is a lot of fun!

I used to have to turn the boost DOWN to 10 PSI to make the car drivable and controllable at the slaloms, and that was on race slicks.

So much depends on both how low the power/torque starts, as to how squirrely the car gets.

[Paul J]

All,
I like this discussion and I'm getting a little more practical as I get older. Is 500 HP needed? NO. Is it fun YESS. The main difference between engines aside from cylinder count is the age. VG30 1984 through the VG33. and SR20 1991 on. At that point the Zcars were on to the VG30DETT. I am a little biased to the VG30 but our GT2 car ran that engine with 300 HP NA with 3 48 IDF carbs in SCCA trim. I love the VG sound and one year at the runoffs in Road Atlanta someone brought their VG powered Dime over to the Nissan banquet. Nice way to clear the room. All the guys were walking outside and the wives and girlfriends wondered where we went. It even had the Magnesium valve covers. SWEET

The big thing with any project is that the owner has to like it, In the dealership days we had quite a few cars the race team built for people. Some were not as well received but the owner loved it. My 510 will probably retain the L20B and dogleg 5 speed, and a customer thinks thats too old school, he would put in a QR25.

BTW our VG30 parts were hand me downs from Electramotive, They were not suitable for 1000 HP anymore but they were great for 300 HP. They did a lot of work on the girdle and drysump pan and the Moldex crank and Crower rods were bullet proof. We ran it in IMSA for a few years before the GTU car was robbed to build the GT2 car. Ran that engine for 6 years and a few Division Championships. Best runoffs finish 4th chassis was a little heavy.

Now the aluminum VG30 block that would keep the weight off the front end, too bad it would be a few cubic dollars to build it, custom crank and all.

Heres a shot of one of my favorite racecars ;(

[icehouse]

16 lbs boost in anything is a lot of fun!

I used to have to turn the boost DOWN to 10 PSI to make the car drivable and controllable at the slaloms, and that was on race slicks.

So much depends on both how low the power/torque starts, as to how squirrely the car gets.

I agree, How low the power starts with a turbo car is tricky to control at times. which to me is ton's of fun! I haven't had a fun car in a long time. I see a race car in my near future though Since I have a garage of my own!

My 510 will probably retain the L20B and dogleg 5 speed, and a customer thinks thats too old school, he would put in a QR25.(

Why would he do that? The VQ sucks IMO open deck, weak valve train, crappy pistons because of the small ring lands, hug stroke. Really the only cool thing about it to me is that it is a die aluminum block. Although that's the engine in my girlfriends altama and it's pretty impressive when it comes to acceleration for what it is. Maybe there is something I'm missing.

[bertvorgon]

At the height of my solo years, I ran a very small turbine housing on my Schwitzer turbo, which gave boost at insanely low speed/RPM, so I had the same throttle response as a good runn'in duel carb'ed car.

Being able to change housings gives you great flexibility for WHERE you want you power to come in. I have 4 sizes of turbine housings. I think sometimes guys do not understand turbine housing size, so maybe miss some tuning latitude.

Also to, even though an engine may show a high boost number on a gauge, how much is actually getting into the cylinder? I have run my 510 years ago against an L20 running an indicated 20-22 PSI, and I run 16, I was faster overall at my lower indicated boost. My cylinder head has had way more work than his, so the cylinder efficiency was just better, plus, a cam that was really developed for my turbo system.

[RonM]

Also to, even though an engine may show a high boost number on a gauge, how much is actually getting into the cylinder? I have run my 510 years ago against an L20 running an indicated 20-22 PSI, and I run 16, I was faster overall at my lower indicated boost. My cylinder head has had way more work than his, so the cylinder efficiency was just better, plus, a cam that was really developed for my turbo system.

Hey Keith,
You've hit on a very good point here. When building my setup I was guilty of overlooking this aspect when designing my SR DET's induction system. I'm running the smallest t3 exhaust turbine I can get, but I'm blowing it through the stock head, valves, and cam. The result is my motor doesn't start producing serious power until upwards of 3,700 RPM, and full boost not until 4,500. Thing goes nuts after that, but it's definitely harder to control, and less usable because of it. The SR head is a good breather to begin with, so I'm hoping that with some cleaning, a stout cam, and fine tuning the mixture and timing I can improve that.

[bertvorgon]

For all of us turbo guys....

Back in the early 70's, when I first started turbo charging, my kit was designed to produce 15 PSI boost, and that was IT. As I progressed with modifications, a whole new world opened up, when I went past those original designed in boost limiting factors. Then, as the engine response went up big time, things happened so fast, you really could not determine WHERE the boost was actually starting to build, or, when the engine went positive.


Here's a little trick to actually test to see when your engine goes positive....

In a safe place, with a straight road ( no traffic ) get a riding mechanic to come along with you, HE/she/they, will watch the boost gauge. Just get the car into third or fourth gear, not too slow, not too fast, but keep the RPM down to around 2,000 - 2,500 or so....then ...

You load the motor by both stepping on the brake and going full throttle at the same time, maybe more throttle initially, but get those brakes on to keep the car fully loaded....the riding mechanic will watch the boost gauge...for when it hits zero.....you watch the tach...he lets you know instantly when the engine crosses over....you note the RPM. This is the true test as to where your motor is really making true boost. You just cannot see it under normal conditions, as things happen so fast.

You get the idea at any rate, you may have to adjust speed or RPM, as your turbine/compressor setup dictates, but, that will give you an idea of the range that it as actually starting to go positive.

In my case also, as I have a pressure gauge BEFORE the throttle, I could see what the pressure drop was over the throttle(S), as a gauge of flow/restriction efficiency. Again in my case, with my BIG carb on there, I had a 1-2 lb differential.

It also tests how good your brakes are......