Jump to content
SAU Community

Recommended Posts

Hi Guys,

The humble r33 GTS25t. we all know it's got alot going for it:

good looks

good power,

solid engine

etc etc

as far as i know, it seems that most of them can get up to 220rwkw on the standard turbo with all supporting mods.

alot of s15s are capable of up to 237rwkw on the standard turbo with all supporting mods.

this is dyno proven with the usual PFC, full 3", cams etc etc everything upgraded except the turbo.

why? i know the RB25det turbo cant handle boost etc, but what about a similar spec turbo to an S15? would it be able to make the same power?

this is also with the usual PFC, full 3", cams etc etc everything upgraded except the turbo.

an s15 upgrading to a GTRS is capable of up to 260rwkws too..

so tell me why is the RB25det only making 280rwkw at the most with a GTRS? :)

it's got 25% more displacement etc, why are s15's so close in comparison in terms of power when on paper, we should have a much better performing engine?

thanks

Link to comment
https://www.sau.com.au/forums/topic/272241-skyline-vs-silvia/
Share on other sites

  • Replies 43
  • Created
  • Last Reply

Top Posters In This Topic

237 is a very specific figure you've got there, I'm always wary when i read dyno reports of 298kw, 252kw - They usualy sound to me like the owner/tuner is chasing some magic target number, and so (not in all cases of course) the engine is probably running a knife edge tune to get every possible last little bit out of it.

The crux of it is, i'd assume that they're totally different engines and that's your inherent difference. Why does an RB25 only have 35 more HP than an RB20, but about 50hp more than an RB30? You're comparing apples and oranges, S15's are much newer cars than R33's and as such i'd expect them to have better engine tech as standard (inc turbo).

Well for one if its a jap spec S15 it has a steel wheeled T28 turbo, so it is larger than the stock RB25 turbo, this is why they make more power on a stock turbo.

As far as turbo vs turbo wise goes on different engines. A turbo will max out at a certain power regardless on what displacement engine it's on. You have to think of airflow wise of the turbo, not so much the capacity of the engine.

The larger displacement engine will make more torque from it's displacement and will spool the turbo up quicker due to having more exhaust gas. However once the turbo reaches it's max effeciency the game is over power wise.

Well for one if its a jap spec S15 it has a steel wheeled T28 turbo, so it is larger than the stock RB25 turbo, this is why they make more power on a stock turbo.

As far as turbo vs turbo wise goes on different engines. A turbo will max out at a certain power regardless on what displacement engine it's on. You have to think of airflow wise of the turbo, not so much the capacity of the engine.

The larger displacement engine will make more torque from it's displacement and will spool the turbo up quicker due to having more exhaust gas. However once the turbo reaches it's max effeciency the game is over power wise.

AFAIK the Jap and Aus S15 were both steel wheeled (compressor and exhaust wheels) and the same size. The only diff in them was the aus is bush bearing and the jap is ball bearing....as far as i knew

Overall though the S15 is a better performance package. It'll out perform a 33gtst in every way out of the box, and mod for mod will continue to do so....

Sorry, should have worded that better. I just ment the S15 has a steel wheeled T28 compared to the R33 which doesn't hence why the S15 will make more power out of the stock turbo.

Edited by PM-R33

A S15 cannot get 237rwkw on a stock T28. Just because its been on a dyno and pulled 237rwkw doesn't mean shit. Hell, my S13 pulled 165rwkw with just an exhaust and pod, anyone with a brain would not that is not possible.

But its been on a dyno, it MUST be true!

you would have to run a dangerous boost level to kick out that power; over 17psi - my mates s15 pulled 187rwkw with all those supporting mods and i pulled 166rwkw with 11psi + step 1 cams.

regardless, an s15 is alot lighter too and with a good suspension setup + tyres will still eat a similar tuned r33

I think the RB will have a better power spread (fatter torque curve), firstly they are 6 cylinder engines which mean a cylinder will be fired every 60 degrees as opposed to 90 degrees on a 4 cylinder and capacity does come into play if you are referring to the RB25.

Don't forget there are other factors too like VVT etc...

Max power figures (regardless of the engine) are not the be all end all.

The humble r33 GTS25t. we all know it's got alot going for it:

good looks

That's in the eye of the beholder.

alot of s15s are capable of up to 237rwkw on the standard turbo with all supporting mods

Unless one of those "supporting mods" is nitrous or active cooling onto your intercooler core, the dynos pulling that figure must be very downhill. Most S15s I've seen max out the T28 at 200-210rwkW.

an s15 upgrading to a GTRS is capable of up to 260rwkws too..

so tell me why is the RB25det only making 280rwkw at the most with a GTRS? ;)

The GT-RS is rated as a 400hp turbo, if I remember correctly. That's all the air it'll flow, full stop. It doesn't matter how big the engine is - if you can get enough exhaust gas through the impeller to flow 400hp worth of air through the compressor then that's all you're getting. Power is made by mixing air and fuel in a fixed ratio, so if you're only supplying 400hp worth of air then your engine, regardless of displacement, is only going to make 400hp.

it's got 25% more displacement etc, why are s15's so close in comparison in terms of power when on paper, we should have a much better performing engine?

In peak power maybe, but the RB25 will be much fatter in the midrange to hit that 260rwkW. Total area under the dyno graph is what's important to people who want to compete in the real world, not just on paper.

Both the S15 and RB25 have VCT.

But only the S15 has VCT rattle. :rofl: It'll sound like a diesel, even if it doesn't make torque like one.

Skyline versus Silvia

Ford versus Holden

WRX versus Evo

Amy Winehouse versus Drugs

Miss R34 versus an informed, intelligent opinion

Ah the eternal arguments....

lol ..I had a feeling that somehow that thread was gonna resurface in some way or another :action-smiley-069:

Skyline versus Silvia

Ford versus Holden

WRX versus Evo

Amy Winehouse versus Drugs

Miss R34 versus an informed, intelligent opinion

Ah the eternal arguments....

bahahahhhhahahahahaaa. straight to the post of the year thread for you young man!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Surely somebody has one in VIC. Have you asked at any shops?  Is this the yearly inspection or did you get a canary?
    • This is where I share pain with you, @Duncan. The move to change so many cooling system pieces to plastic is a killer! Plastic end tanks and a few plastic hose flanges on my car's fail after so little time.  Curious about the need for a bigger rad, is that just for long sessions in the summer or because the car generally needs more cooling?
    • So, that is it! It is a pretty expensive process with the ATF costing 50-100 per 5 litres, and a mechanic will probably charge plenty because they don't want to do it. Still, considering how dirty my fluid was at 120,000klm I think it would be worth doing more like every 80,000 to keep the trans happy, they are very expensive to replace. The job is not that hard if you have the specialist tools so you can save a bit of money and do it yourself!
    • OK, onto filling. So I don't really have any pics, but will describe the process as best I can. The USDM workshop manual also covers it from TM-285 onwards. First, make sure the drain plug (17mm) is snug. Not too tight yet because it is coming off again. Note it does have a copper washer that you could replace or anneal (heat up with a blow torch) to seal nicely. Remove the fill plug, which has an inhex (I think it was 6mm but didn't check). Then, screw in the fill fitting, making sure it has a suitable o-ring (mine came without but I think it is meant to be supplied). It is important that you only screw it in hand tight. I didn't get a good pic of it, but the fill plug leads to a tube about 70mm long inside the transmission. This sets the factory level for fluid in the trans (above the join line for the pan!) and will take about 3l to fill. You then need to connect your fluid pump to the fitting via a hose, and pump in whatever amount of fluid you removed (maybe 3 litres, in my case 7 litres). If you put in more than 3l, it will spill out when you remove the fitting, so do quickly and with a drain pan underneath. Once you have pumped in the required amount of clean ATF, you start the engine and run it for 3 minutes to let the fluid circulate. Don't run it longer and if possible check the fluid temp is under 40oC (Ecutek shows Auto Trans Fluid temp now, or you could use an infrared temp gun on the bottom of the pan). The manual stresses the bit about fluid temperature because it expands when hot an might result in an underfil. So from here, the factory manual says to do the "spill and fill" again, and I did. That is, put an oil pan under the drain plug and undo it with a 17mm spanner, then watch your expensive fluid fall back out again, you should get about 3 litres.  Then, put the drain plug back in, pump 3 litres back in through the fill plug with the fitting and pump, disconnect the fill fitting and replace the fill plug, start the car and run for another 3 minutes (making sure the temp is still under 40oC). The manual then asks for a 3rd "spill and fill" just like above. I also did that and so had put 13l in by now.  This time they want you to keep the engine running and run the transmission through R and D (I hope the wheels are still off the ground!) for a while, and allow the trans temp to get to 40oC, then engine off. Finally, back under the car and undo the fill plug to let the overfill drain out; it will stop running when fluid is at the top of the levelling tube. According to the factory, that is job done! Post that, I reconnected the fill fitting and pumped in an extra 0.5l. AMS says 1.5l overfill is safe, but I started with less to see how it goes, I will add another 1.0 litres later if I'm still not happy with the hot shifts.
    • OK, so regardless of whether you did Step 1 - Spill Step 2 - Trans pan removal Step 3 - TCM removal we are on to the clean and refill. First, have a good look at the oil pan. While you might see dirty oil and some carbony build up (I did), what you don't want to see is any metal particles on the magnets, or sparkles in the oil (thankfully not). Give it all a good clean, particularly the magnets, and put the new gasket on if you have one (or, just cross your fingers) Replacement of the Valve body (if you removed it) is the "reverse of assembly". Thread the electrical socket back up through the trans case, hold the valve body up and put in the bolts you removed, with the correct lengths in the correct locations Torque for the bolts in 8Nm only so I hope you have that torque wrench handy (it feels really loose). Plug the output speed sensor back in and clip the wiring into the 2 clips, replace the spring clip on the TCM socket and plug it back into the car loom. For the pan, the workshop manual states the following order: Again, the torque is 8Nm only.
×
×
  • Create New...