I took my Buggy for it's first highway cruise today. At 70mph I'm at 3400rpm. This is with a 4 speed VW transaxle. What's normal for Imprezza/WRX?

Edited August 25, 201015 yr by Speedbuggy

That's rly hard to tell since the FD gear is different along with the amount of gears and if it has a tq converter and over drive

I'm not asking if what I'm seeing is normal, I'm asking what's normal for an actual Subaru with a similar engine like a WRX or STi.

Like he said it's based off the final drive and if it's a manual or not.. Not a WRX/STI engine as you said.. For your info at 80 MPH in my car I'm at near 4K rpms.

I'm more asking just to get a feel for what RPMs the engine should be comfortable maintaining for long periods. 4k at 80mph is about what I'm at too.

My legacy with the 3.9 gears and long 5th gear turns 3k at 70, 3.5k at 80.

The 99 outback with 4.11 gears and short 5th runs about 3.5k at 70 and around 4k maybe a bit higher at 80.

 

These engines are fine running continuous at 4k in my opinion, they're small engines designed to run at higher RPMs.

 

Hope that helps.

The lower the better but these seem to do fine running ~3k rpm.

I prefer to keep mine in the 2000 - 2500 rpm range if I'm driving for long periods of time.

The aviation people run them at like 5 grand continuous and they do just fine.

My 99 OBW with a 95 2.2 5 speed runs just over 3000 at 70.

Are you aware of the reverse cut ring and pinion gears that you can have installed in a subaru 5 speed trans? Now you can run a complete subaru drivetrain in your VW...no adapter plates etc.

I am going to tackle this in my 79 bay window( currently running a 78 Porsche 912s engine with type 4 fuel injection) this winter. Search reverse cut subaru gears. They are in Australia. As I remember the pics show a Manx buggy.

3400 rpm at 70mph seems a bit high but not overly so. They might have set yours up for better performance and take offs at lower speeds rather than for long distance cruising. How many gears does your Beetle transmission have?

 

If top speed matters to you, it sounds like you would definitely hit the gear limited top speed on that set up well before it would be drag limited.

he said a 4 speed in the OP. Since the original engine only had like 40hp it couldn't run such low RPMs at high speed or it wouldn't move.

4 spd, ok thanks I must've missed it. That would contribute to having a higher rpm in top gear then since the gears have to spaced further apart than they would in a normal Subaru 5spd trans, or the STi 6spd.

Not to get off topic but the 95 is it gear limited?

Not to get off topic but the 95 is it gear limited?

 

Most legacys are governed at 110 or 112mph. if you pull the speed censor you are gear limited at something like 135 with 3.9 gears and the long 5th at 6k RPMs (ej22 redline)

Most legacys are governed at 110 or 112mph. if you pull the speed censor you are gear limited at something like 135 with 3.9 gears and the long 5th at 6k RPMs (ej22 redline)

 

I was not aware my car had a speed limiter.. I never wanted to hit those speeds with the stock 14" wheels

I was not aware my car had a speed limiter.. I never wanted to hit those speeds with the stock 14" wheels

 

That's why it has the speed limiter. Most 14" tires are "S" speed rated which is 112 mph. The risk of a blowout multiplies something like 5 times for every 5 mph over the maximum rating. So at 122 mph you are ~25 times more likely to blow out a tire than at the tires "safe" rated maximum speed of 112 mph.

I took my Buggy for it's first highway cruise today. At 70mph I'm at 3400rpm. This is with a 4 speed VW transaxle. What's normal for Imprezza/WRX?

 

That's the same or a little lower RPM than my '06 STI, IIRC. There's some talk of the maximum fuel economy happening right below 4,000RPM. Any higher than that, and there's extra fuel being dumped in for boost. I don't know the specs of your TD04/05 vs. my VF39, but I'd guess it's close to the same.

 

That RPM seems good for your setup. Cruise in 4th, and if you want power, a downshift to 3rd would likely get you right into boost territory:burnout:

 

Jacob

That's why it has the speed limiter. Most 14" tires are "S" speed rated which is 112 mph. The risk of a blowout multiplies something like 5 times for every 5 mph over the maximum rating. So at 122 mph you are ~25 times more likely to blow out a tire than at the tires "safe" rated maximum speed of 112 mph.

 

 

 

When I put the 17 wheels on I might see where it's at highest I ever been was 110 and I did not feel the car slow down unlike my 98 forester.. at about 118 mph you felt the speed limiter kick in.

Thanks for the replies everyone.

I am aware of the reverse cut gears for running a subaru tranny in this configuration and may go that route down the road, but it appears I'm fine running at 3400rpm for long periods, so I'll stick with this for now.

 

As for top speed, that's not a concern. These buggy bodies tend to start getting 'flighty' at high speeds. Most it'll ever see is what it tops out at in the 1/4mile.

Adding my two cents today. Sorry to be late for the party.

 

Anyway, here's the data:

 

1997 Impreza L wagon

70 mph (from GPS); 72 mph on speedometer

3337 rpm (from scangauge II) in 5th gear

4.111 rear diff

TY752VB3FA transmission (JDM 5MT) has 0.825 ratio for 5th gear

195/60-R15 tires

 

I did notice a shift of about 300 rpm in 5th at that speed when I switched from the 3.900 (stock) to 4.111 setup.