A few engine questions, wanting to increase power

[kristianbowler]

Hi Everyone! I'm new here and I'm new to the SR20DET engine! Finally purchased my dream s15 so I'm mega happy!

I'm now looking to increase the power of my engine and I have a few questions I'm hoping you all can answer for me, so ill just get right to them!

I'd like to aim for as much HP as possible without forging but we'll see how the future goes!

1) What can the standard internals take (standard question that I presumes been asked 1000 times!)

2) Whats the standard turbos HP capability? (Infact what is the standard turbo?)

3) Whats the engine capable of forged?

4)If I do decided to go forged where would be my first call for pistons, rods ect... (i.e what brands are best or commonly used?)

I have a small plan in mind, does this sound reasonable to everyone?


Target of 450HP
Free flow air filter
Free flow exhaust (custom made to suit the turbo, vband)
Walbro 255
Electronic Boost controller (probably AEM)
FMIC Hardpipe
Tubular top mount manifold
740cc nismo injectors
Z32 AFM
GT3071r T3 divided .82ar housing
External Wastegate (Need to research these)
Uprated dump valve (Need to research these)
Cooler spark plugs (Already fitted)
Aftermarket cams (undecided which cams yet; id need to research duration and lift ect..)

Anyone have any similar spec s15s?

Thanks guys!

[saddened]

Don't make the mistake everyone makes and upgrade the engine imediately. Drive it stock for a while, then go from there and every time you upgrade do it with high HP in mind. On the way you will either change your mind, run out of money or motivation but at least you will have a car on the road and not a shell and some pieces of what used to be a good engine.

[autosri]

You would need to add a gearbox conversion to that list as the stock ones are weaker than the engine I'd say

[jbsauce]

Honestly think you should do more reading before asking all this stuff, someone planning a 450bhp engine shouldn't be asking what the engines standard turbo is, sorry.

[Chriscooke]

450bhp likely won't last long on a standard block. I'd suggest a mhg and uprated head studs at a minimum. I'm going to have my engine built soon with a similar power in mind. 350-400bhp is normally considered the limit of a stock motor.

Standard turbo will see you a little over 300bhp at the flywheel, forged motors are capable of what you're wallet can afford, stroker cranks and liners etc will increase its abilities. Most seem to go with cp pistons and manly rods which is likely the route I'll be taking.

Don't forget you'll need a proper clutch to hold that power and I'd think about going for a chunkier fuel pump than the walbro.

I'd go for a gtx turbo in a similar size as you listed as they spool quicker and make more power

[hooky]

There is a very tried and tested route of going down the staged tuning route, IE up to stage 3a (Horsham Developments) for around 360ish HP, which is around the point where the standard internals/gearbox are still happy.

However, above this, things start to snowball, think Stand-alone ECU, fully forged, stronger gearbox and associated running gear etc!

If your goal really is 450hp, then you will need to skip the staged route and jump straight into a bigger GTX series turbo, and bigger injectors (1000cc) full stand alone with all the trimmings (boost control, closed loop wideband etc)

In all honesty, the enigines limit is as big as your budget!....

[Chriscooke]

I thought 740's would just about stretch to 450? You can get 850cc's in side feed too but don't 1000cc only come in top feed and require a new intake?

[hooky]

I thought 740's would just about stretch to 450? You can get 850cc's in side feed too but don't 1000cc only come in top feed and require a new intake?

Personally i've never run 740's, but i used to see around 80% duty cycle on 850's at 430hp, but my point is that if you're going to skip the staged limit....Go Big!

[Chriscooke]

Fair comment

[green_rs13]

a reliable 450WHP will cost more than an S15..

[kristianbowler]

You would need to add a gearbox conversion to that list as the stock ones are weaker than the engine I'd say

Conversion? What do people commonly convert to? I like the idea of a 6th gear for motorway journeys ect... does the 6 speed have a weak point?

Honestly think you should do more reading before asking all this stuff, someone planning a 450bhp engine shouldn't be asking what the engines standard turbo is, sorry.

Thanks for your utterly useless and pointless unwanted comment. Just because I'm unsure what turbo the engine runs does not mean my mechanical skill is any less. How do you know what the turbo is...? at some point you've either read it or someone's told you. I had an idea what the standard turbo was but I wanted to confirm this by people who know more than me, if YOU read properly you can see that I said i'm new to these engines and car, thus my knowledge is limited.

I spent most of my experience building rover k series turbo engines.

450bhp likely won't last long on a standard block. I'd suggest a mhg and uprated head studs at a minimum. I'm going to have my engine built soon with a similar power in mind. 350-400bhp is normally considered the limit of a stock motor.

Standard turbo will see you a little over 300bhp at the flywheel, forged motors are capable of what you're wallet can afford, stroker cranks and liners etc will increase its abilities. Most seem to go with cp pistons and manly rods which is likely the route I'll be taking.

Don't forget you'll need a proper clutch to hold that power and I'd think about going for a chunkier fuel pump than the walbro.

I'd go for a gtx turbo in a similar size as you listed as they spool quicker and make more power

I see! Well I'd like to aim for the 400HP mark as the car is a daily and I'm unwilling to forge for the foreseeable future (but you never know).

Cost isn't so much an issue to me as its a long term project! Clutch ill start doing my research on

A GTX series never crossed my mind actually! Ill have a look around thanks!

There is a very tried and tested route of going down the staged tuning route, IE up to stage 3a (Horsham Developments) for around 360ish HP, which is around the point where the standard internals/gearbox are still happy.

However, above this, things start to snowball, think Stand-alone ECU, fully forged, stronger gearbox and associated running gear etc!

If your goal really is 450hp, then you will need to skip the staged route and jump straight into a bigger GTX series turbo, and bigger injectors (1000cc) full stand alone with all the trimmings (boost control, closed loop wideband etc)

In all honesty, the enigines limit is as big as your budget!....

Sweet! Standalone is the plan as with all the other "tiff" bits. As mentioned above a GTX Series turbo never crossed my mind so I may head down that route

a reliable 450WHP will cost more than an S15..

Part and parcel of the modification and power scene unfortunately!

[Chriscooke]

The six speed box isn't the strongest of boxes but then either is the 5 speed on the 14's. A lot of people are now converting to the cd009 box from the later 350z's with a conversion kit. Another option is an rb25box but then you lose the 6th gear iirc.

[Jonny Wilkinson]

Jbsauce's comment was only useless because you didn't take it on board mate.
If you buy a car to tune it, you will come across as more credible if you know your budget, the reasons for your​ target of 450 bhp and the basic spec of your car as standard. You could quite easily spend a productive month of evenings sucking up a fraction ofl the high quality tuning info in tech s14 before starting your thread. That was his point and is not unreasonable just not to your liking

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[CMR]

This forum and the s15oc has countless technical and project threads answering pretty much every question you have asked.
Why don't you use the search function?

I also fail to see how you know you want 450bhp without (as far as I can see) knowing really anything about S15's or s bodies in general...It's a bit of a odd one if I'm honest.

Edit. Just realised you posted a thread not long back saying you have bought your first RWD and first Japanese car. Honestly - please just drive it for a year before even considering upping the power to anywhere near 450bhp.

[zeppelin101]

Standard turbo is a GT2560 / GT2560r. Not all S15s came with ball bearing turbos, but Garrett will only sell you a ball bearing unit these days.

I wouldn't be buying a regular GT series turbo these days if you're wanting to make proper performance. The Garrett GTX and Borg Warner EFR units are much more efficient, with more compressor map width and higher pressure ratio capability. A lot of the GT units (with some exceptions on the smaller end of the scale) are kinda rubbish to be honest.

If you want a 6 speed gearbox your best bet is going to a Z33 swap, but these cost a small fortune. RB25 and Z32 5 speeds are also popular swaps. Gearbox life will depend entirely on how you drive it and how your car is setup. If you have lots of grip and you're smashing through ratios the forcing through the gearbox is very high and you'll break it very quickly. They are ropey from anything over 400Nm / 300hp if driving on track in my experience.

Were I in your position (again), I would drive it as is for a while and maybe do the appropriate mods for H-dev Stage 2a which is relatively inexpensive and will get you up to the 290hp mark. It makes for a pretty quick car; you'll need a lot more power to make up for the loss in low end torque to go much faster in my experience when sticking with the 2.0l.

[Matas]

I'm on the same boat as many here, I wouldn't really recommend the jump from a stock s15 to planning a 450bhp s15. Being your 1st rwd car and being a sbody specifically you should be careful. Some reading and getting to know your car is definitely needed. Everyone on here is always happy to help, however when you fail to do some basic research yourself, people won't be as happy. As hooky said, I'd personally recommend going down the staged route once you're ready and pick up a Horsham Developments chip and everything required to go along with it. As always and I'm sure you know yourself, give your brakes, suspension and tyres attention before power.

[jbsauce]

Jbsauce's comment was only useless because you didn't take it on board mate.
If you buy a car to tune it, you will come across as more credible if you know your budget, the reasons for your​ target of 450 bhp and the basic spec of your car as standard. You could quite easily spend a productive month of evenings sucking up a fraction ofl the high quality tuning info in tech s14 before starting your thread. That was his point and is not unreasonable just not to your liking

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Just the mentality people have these days, call them out for anything and they take offence to it. Everyone wants spoon feeding, or 450bhp so he can tell the 'lads' in maccies its 450bhp...

[jbsauce]

Also, if you have all this experience building turbo rover engines, you should be able to use a injector calculator and know that 740cc injectors wouldn't support 450bhp. You look a bit silly with the salty replies...

[Chriscooke]

Love it here, sombody new comes along and asks for advice and then everyone turns in to self righteous gits. Either answer the question or don't post.

[autosri]

I think 3a Is more than enough for than a road car gets a bit silly after that you would have to be so carull everywhere it would stop being fun and no need to start getting into forged stuff and the gearbox is semi happy and you can use a organic clutch still

There isn't much day to day that can keep up

I'd recommend a decent diff like a 3.9 or 4.1 will make it feel so much quicker I've got a 4.3 2way and it's a bit short for cruising but feels rapid round town