Getting power from a 5SFE without forced induction

[mrturrari]

I'm seeing a lot of posts with people asking how to make power on a 5SFE and getting some pretty unhelpful responses. So I put this together to maybe help them out:

Getting power from a 5SFE without forced induction

First let's just get this right out in the open. NA power is never cheap and it is not something you can just throw together expecting great results. You can't just turn up the boost to hide mismatched parts or poor design like many of the turbo guys do. The benefits though are quick throttle response and predictable, consistent power which is very desirable at the limits. The power comes from the combination of all the right parts and synchronicity of design so everything is going to have to be working together to give you a great results.

Ok so where do you start? As has been said by myself and others many times, "Always start with the cams". I'll give TomsMR2 credit for spreading that very important point. More then anything else, the cams determine where your torque will be and how much of it you will have. The cams are responsible for the highest torque peaks you see in any dyno graph. Everything else, valve size, valve angle, ports size and shape, whatever is all secondary to this. These other things are not going to be significant road blocks until you are trying to get all of a motors potential and we are going to be no where near that. The problem is you need to plan ahead so your cams match your ultimate goals. Don't buy a mild set of cams and expect them to be able to take you much past 150rwhp.

The second most critical part is the header. A good header will take torque from places you don't need it and add to places you do. Pipe diameter and primary length are the two most important things to look for although you should also make sure the pipes are mandrel bent with smooth transitions and a good collector.

The third most important is the exhaust. Mainly it just needs to be smooth and not too restrictive or too big at the RPMs where you want to make power.

For practicality I am going to split 5SFEs into 3 groups:

Mild Build

First group is the mildly built 5SFE. 99% of all current 5SFEs fall into this category. Cams are either stock or mild enough not to require tuning (294 grind equivalent) or fuel system modification. These will have all bolt-ons, just the stuff you find from board vendors or on ebay. They would include the basic I/H/E (intake/header/exhaust) and sometimes things like a shaved head or a lightened flywheel. We have all seen these builds producing everywhere from 110-145rwhp and are often still reasonable gains for the money.

For this level a header with 1-5/8" primaries and 28" or longer runners will probably give you the best overall power. Generally a 4-2-1 header will give you less of a peak but a broader power band if that is what you want. Avoid really short runners and anything with 1-7/8" or larger outside diameter primaries. Those would put the torque gains beyond the power range of the cams. The exhaust should be at least 2" up to 2-1/4" OD and be as smooth and high flowing as possible. Mandrel bends are best. A stock turbo exhaust works ok at this level and if you need a CAT to pass inspection then get a high flow one to put somewhere before the muffler.

If you pick your parts right you can spend less then $1000 and gain more then 30rwhp which puts you right up there with the gen2 3sge but with more torque. Focus on the cams, the header and the exhaust. All other mods at this level are minimal gains.

(Bare minimum)
Colt cams or Webcam 294: $400-600
Shims to install cams: $0-140
Header: $150
Exhaust: $100-600

Performance Build

The second group is for 5SFEs with street performance cams. On an NA anything above the 294 with more lift (up to 9mm) or duration up to a 101 grind or 272 advertised duration in my opinion would be in this group. These require larger injectors and tuning to be safe. They also generally require upgraded valve springs (3SGTE for rev1 or 2JZGTE for rev2) because of the extra lift. Check your coil bind and if you don't have 0.360" travel from the base circle then upgrade them.

The header needs to be something a little more purpose built but some of the ones you can buy will do. Runners can be a little shorter but I wouldn't go less then 24" and the primary diameter can be a little bigger if you want more top end. 1-3/4" diameter should be about perfect for this level. Power will move up closer to red line between 5000-6000rpms so you will want a 2-1/2" high flowing exhaust.

You don't have to raise the red line or do any bottom end mods to have usable power but at this level it is something to consider because with these cams you will able to use it. If you already have a piggyback then it is an easy thing to overclock the 5s ECU and retune. It actually got rid of some of the querkiness I had with the larger injectors. The only concern is the rod bolts when you start going past 6500rpms. It is a good idea if you exceed this to grind the crank and put in 3s rods or find an upgraded 5s bolt (no one has found some yet that I have seen for a reasonable price except the slightly stronger later model 5SFE ones from Toyota).

This is also the level where some other mods are going to start to have a greater effect like having a custom intake manifold, bigger throttle body, head porting, larger valves and higher CR. Again if you pick your parts right you can get some decent gains for reasonable money and still have a little room to grow. Since no one has dynoed one of these yet I can only guess on power levels. Probably 150-180rwhp depending on what other supporting mods are done. The highest on record 5SFEs fall somewhere in between Mild and Performance because they had the fuel control but only mild cams. A 150rwhp or higher 5SFE should be able to be built for for less then $2000 if you find the right deals and install everything yourself.

(Bare minimum)
Webcams 763 or 101 grind: $600
Shims to install cams: $0-140
Valve springs: $50-100 plus a head gasket if you have to pull the head to install them
Header: $150-300
Exhaust: $100-600
295cc or 315cc Injectors: $50-100
Fuel Controller: $250-700
Wideband O2 (if you want to tune it yourself): $250-450
Tuning (on a dyno if you need someone else to tune it): $100-400

(Going to town)
3s rods: $200-500
Shaving the head (poor man's CR increase): $40-80
Custom Pistons (rich man's CR increase): $650
+1mm valves: $400-600
Porting $0-800
Rebuild costs: $300-500
Custom Intake manifold: $200-600
60mm Throttle Body: $100

Racing Build

This is where things start to get serious and parts need to be custom made. All the things that uninformed people always list as needed to get power from a 5SFE seem to fall into this. Cams at 288 advertised duration or higher with lifts from 9mm to as high as 13mm, shimless buckets, double valve springs, oversized valves, professional head work, EMS mandatory, forged rods, custom high CR pistons, upgraded ignition, high flow oil pump or dry sump, balanced bottom end, light weight everything, custom header, custom intake manifold, you name it. Racing is expensive so be prepared to empty your wallet but the sky is the limit. If you really want to build a 5SFE to its potential then contact me and I can help you figure out what you need.

I know this is a pretty general overview but it should be a good start for someone. Helpful comments or questions are welcome in this thread but if you want to expound the glories of the engine swap or forced induction please put it somewhere else.

Thanks,
MrTurrari

[shimric]

Nice read mang. Good job.

[DenverMR2]

Thanks for giving us 5S people some hope hope you also do a forced induction part

[kbrew8991]

what would really be useful is some info on making the best of stock head, intake mani, and cams - for the guys that race and care about classing alot of places won't let you touch those items without getting put up against some stupid competition

I'll be probably forging down that road on my own around the winter of '09 or so This build will be to fit SCCA's Improved Touring A division:

looking at doing the following
- custom header with some ideas garnered from Mustang drag racing guys that run stock heads to help out with scavenging exhaust out of these craptacular stock exhaust ports
- exhaust (short & light, maybe a muffler)
- intake (again, probably more weight reduction than power, but every bit helps)
- either Megasquirt stuffed into factory ECU housing or some sort of piggyback, not sure... (need to read rules again, but mainly for fuel curve adjustment)
- need to look again but I'm pretty sure I can mix & match stock parts (so 93 cams on 91 head, or just the 93 cams & head.. whatever is better)

there are also some small internal stuff I'm allowed (extra 0.5 compression ratio being the biggest help) but I'd be curious what the experts here would expect that to make with those 5 items attached to a stock 91 MR2 5SFE, or if I'll need to delve into doing all of that plus the $$$$$ minor internal stuff to squeeze every last drop out....

some of the cars I'll be competing with are putting down upwards of 145-155whp & similar torque... though they're heavier, FWD, shaped like a brick, etc so as long as I can get some decent power (maybe high 130s-low 140s and similar torque) out of the 5SFE I see no issues being on a level playing field with them

would you expect your recommended header sizes in the "mild build" section to mesh well with someone stuck with stock cams? I also noticed no mention of intake - just because it shows no gains, hurts power, or just isn't enough for the budget oriented guy to worry about?

I'd be neat to see a "stuck with stock cams"/"external bolt-ons only" section

[mrturrari]

Let me post another write-up I was working on in the background:

How to size headers for you 5sfe

If you have read and understood what I have said in my "how an engine really works" writeup (yeah I know you guys haven't seen that yet) then you understand that pipe size can be directly correlated to a torque peak at a particular RPM given engine displacement and volumetric efficiency. The balancing point where greater pressure differential starts to move fewer molecules of air instead of more happens in exhaust gases because of higher temperature at about 240-260 feet per second. This can be used to calculate the optimal size for header primaries and exhaust pipes.

One formula found here Exhaust Header Design Comments can be used for header primaries in a 4-1 or 4-2-1 header. The formula is

Area of Primary Pipe = RPM × Cylinder Size ÷ 88,200

or written another way

RPM = Area of Primary Pipe x 88,200 ÷ Cylinder Size

This formula has a few assumptions built in like volumetric efficientcy and the temperature of the exhaust gas but it is still a good way to estimate how big the primaries need to be on your header and where you are trying to make power. Using a stock 5sfe as a base and assuming a wall thickness of 0.055" on your pipes you get the following numbers:

Displacement of a stock 5sfe: 87mm(3.4278")x 91mm(3.5854") 540.95cc (33.086") per cylinder
Primaries at 1-3/8" make peak torque at 3352rpm
Primaries at 1-1/2" make peak torque at 4045rpm
Primaries at 1-5/8" make peak torque at 5224rpm
Primaries at 1-3/4" make peak torque at 5631rpm
Primaries at 1-7/8" make peak torque at 6522rpm

The primary tube diameter in my opinion is the first and most important factor in determining the right header for your engine but other factors will also influence where your header will make power. The primary and secondary length will also influence power made above and below the torque peak. A good illustration of how this works is in this article:

Exhaust & Header - Tech - Exhaust Gas Tech - Circle Track Magazine

It basically says that shorter pipes will move power from below to above the torque peak and longer pipes will do the opposite. The curve leans as you change the pipe length depending one which direction you go. This is all because of wave tuning and getting either a higher or lower pressure at the exhaust valve when it opens or before it closes. It is important to note that unlike with pipe diameter, wave tuning of this sort is very dependent on cam duration. The timing of the events is critical to determine the correct length so you will need to have some information about the cams you will be using specifically the exhaust valve closing angle.

A. Graham Bell in his book "Four-Stroke Performance Tuning" takes a slightly different approach to calculating primary length and diameter He has decided to calculate length first and then use that to also determine pipe size. In the end it is still the same basic principal at work. You choose a target RPM and then size your pipes to give you power at that RPM. He uses this formula:

Primary Length = (850 x ED / rpm) -3

ED is the number of degrees before BDC that your exhaust valve closes plus 180.

To get primary pipe diameter you then use:

ID = sqrt(Cylinder Volume in cc / ((Primary Length +3) x 25)) x 2.1

On a stock 5sfe with an ED of 210, that is just a guess on my part assuming lobe centers of 110 degrees and a duration of 200@0.050", you get the following:

According to Bell stock cams will require
Increase torque at 3500rpms length should be 48" and ID should be 1.37" which is about 1 1/2" OD.
Increase torque at 4000rpms length should be 41.6" and ID should be 1.46" which is close to 1 5/8" OD.
Increase torque at 4500rpms length should be 36.7" and ID should be 1.55" which is just over 1 5/8" OD.
Increase torque at 5000rpms length should be 32.7" and ID should be 1.63" which is 1 3/4" OD.
Increase torque at 5500rpms length should be 29.5" and ID should be 1.77" which is between 1 3/4" and 1 7/8" OD.
Increase torque at 6000rpms length should be 26.8" and ID should be 1.79" which is close to 1 7/8" OD.

You can see that the two different methods give similar results within a few hundred RPMs. When dealing with 4-2-1 headers you treat the overall length and primary diameter as if they were 4-1 headers and then, from Bell's book, use the formula IDS = sqrt(ID x ID x 2) x 0.93 to get the secondary diameter. So for a 4-2-1 header that had 1-5/8" primaries the secondary diameter would be 2" ID or about 2-1/8" OD. If you think about it that secondary is flowing 2 cylinders worth of exhaust but those pulses are happening twice as often. I'm not sure at this point if you could use that formula because of that but I don't know for sure.

The length of primary vs secondary on a 4-2-1 header is a little more of a black art. A. Graham Bell suggests that the primaries be at least 15" long and the secondaries what is left. It's a good place to start. In my opinion a 4-2-1 header will act like progressively weaker versions of 4-1 headers of the same length as the primary, primary plus secondary and secondary lengths. So if your total length is 36" and your primaries are 26" you will have peaks showing up at 4500rpms, 6000rpms and weakest secondary peak would be beyond what the motor is capable of revving. It is more complex then that though because of all the combinations of refections you can have in a 4-2-1 header. You end up with weaker but more waves and that is why they generally give you a broader power band. You can use this to your advantage by keeping your primaries and secondaries different lengths so you have more peaks. If you made them the same lengths then you would end up with fewer peaks that were multiples of each other, say 4000rpms, 8000rpms and 2000rpms. Not the best thing for having a usable power band. You want to pick peaks that are closer to each other 500-1000rpms apart for having a good usable power band. That part is more my opinion and not backed up by any data.

Lastly remember that both pipe sizing and length are robbing Peter to pay Paul. When you move the torque peak up you will also loose some torque down lower because air cannot as efficiently flow through that larger pipe at a lower rpm. And with wave tuning for every rpm that you can get a low pressure at the exhaust valve at closing there will be another rpm where it become a higher pressure and you will loose power. The trick is to get them in places where they won't negatively effect your power band.

[mrturrari]

Originally Posted by kbrew8991

I'd be neat to see a "stuck with stock cams"/"external bolt-ons only" section

They take all the fun out of it.

Originally Posted by kbrew8991

- custom header with some ideas garnered from Mustang drag racing guys that run stock heads to help out with scavenging exhaust out of these craptacular stock exhaust ports
- exhaust (short & light, maybe a muffler)
- intake (again, probably more weight reduction than power, but every bit helps)
- either Megasquirt stuffed into factory ECU housing or some sort of piggyback, not sure... (need to read rules again, but mainly for fuel curve adjustment)
- need to look again but I'm pretty sure I can mix & match stock parts (so 93 cams on 91 head, or just the 93 cams & head.. whatever is better)

there are also some small internal stuff I'm allowed (extra 0.5 compression ratio being the biggest help) but I'd be curious what the experts here would expect that to make with those 5 items attached to a stock 91 MR2 5SFE, or if I'll need to delve into doing all of that plus the $$$$$ minor internal stuff to squeeze every last drop out....

For the header, I would take a look at your torque curve and decide where would be the best place to increase torque to help you be more competitive. You will not be able to raise your peak HP unless it happens where you are "on cam" but you may be able to negate some of the fall-off in the top end while still gaining some in the middle. What I just posted above should help you figure that out. If you bore it at all you need to redo the numbers. The 5SFE ports aren't too bad but still smaller then the pipe you will end up with. That is a good thing though. You will have a step that will help prevent reversion just try to line the bottom of the pipe up more with the port so there is more step at the top.

For the exhaust you want it smooth, short and just big enough around not to restrict you where you need it. I haven't seen any good ways to calculate that but I am guessing 2" or 2-1/4" pipe. The exhaust pipe size effects where you make torque as well using the same principal as the header I just don't know the formula for it.

An intake will help a little bit but the stock one is a pretty good size for the stock cams and VE. If you make one keep it as short as possible, like 16-18" while still getting cool air and keep it in the 2" to 2-1/4" diameter range. Also if they allow you to use a K&N style filter try to get one with a built in velocity stack or make one yourself. The rule of thumb for intakes is to get the air moving at about 180fps at your highest flowing RPM.

Definitely raise the compression to 10:1 and tune it with a Megasquirt. Jim Snodgrass got much of his power from tuning.

The 93 cams are probably a no-go. They take significant modification to put into a 91 head, either changing the base circle or changing the valves and spring heights.

[Final13]

mrturrari, ive been seeing the same kinds of posts...been waiting for you to chime in, great work. sticky this!

[kbrew8991]

so swapping to the 93 head & cams as a unit (which I can do) is the way to go then eh... they are worth upgrading to, right?

I might try the head & cam upgrade and actually do the computer first to see how much of the drop off up in the RPM band is from pig-richness before deciding on header sizes, lengths, etc. I figure it may not be alot, but it'd be best to know before shelling out $$$ to my fabricator friend if it shifts 500-1k rpms or something

I'm probably looking at an operating range of 4,000-6,500 with the stock trans gearing and final drive. I'd be nice to have torque peak about 4500 and have it hang on to decent torque out as far as it can after that... would have a nice punch off the corner, after each shift and hopefully pull the gear well on top of that

6500 would put realistic end-of-straight speeds in the high 120s, low 130s which is right where it needs to be to run with these guys door handle to door handle into the braking zone where the mid-engine weight distribution & those great MR2 brakes are going to kill 'em

[mrturrari]

Thanks guys. Feel free to add what you know or correct me if I am wrong about something.

[mrturrari]

KBrew,

I don't know if the 93 would really be an upgrade It's hard to tell because they have less duration but more lift. That's a little better for turbo charging but for NA the 91s might have a very slight advantage. The torque curves look almost identical from what I have seen so I truthfully don't know. Adjust your valve clearance on the tight side to get a little more lift. lol

So in your case since you have to live with the stock cams and your not really worried about loosing low end, I would try 1-5/8" primaries and then make them shorter then usual, maybe 24-28". I have 1-5/8" with 28" long runners on my car right now and it does improve the torque in the 4000-4500 range even before I upgraded cams. Another option would be to pick a higher torque peak, say with 1-3/4" pipes, and use longer runners, maybe 28-32", to pull up the curve below that. That may not be as effective though. There is still so much in header building that is going to be trial and error. The formulas just get you in the ballpark.

[mr2greasemonkey]

Great post!

[TomsMR2]

theres a page with some big block chevy or ford guys doing some header testing on full blown, fully built high compression large v8's in racecars.. on those large v8's they were making more power with 1.5 inch header primaries.

if a big block v8 can use 1.5 inch primaries and make the most power, you gotta wonder why they sell 5sfe headers with 1.75 primaries.. i think my 3sge header had 1 5/8th or around there, and its by far the best header ive ever had on an mr2.. my steel tubular modified camry header isnt too bad either, beats the hell out of an ssac. i think it would be interesting to see where a 1.5 puts your power.. i think you'd up response quite a bit and still flow a reasonable amount towards the stock cammed limit. remember, headers are made for an effective range, not just a peak figure. its better to gain 10hp for 3000rpm than gain 15 for 1000rpm.

tried a bunch of secondary lengths.. i think i was using 1.75 secondaries, maybe they were 2.0.. but the super short y-merge produced a significant bump in power..

also keep in mind that the stock b-pipe is 1.5 inches. its not even a smooth 1.5 inches, its just all over the place with lips and weird metal blocking the flow. you can have a great header and it'll be negated by the stock b-pipe.

i think a smooth, mandrel 2.0 exhaust and flex section would give the best gains with the stock cams. i went 2.25 just because its what i had laying around.. i think 2.0 would be better. for reference, a RSX-S makes 200hp with a 2.0 inch mandrel bpipe.. a big, long, front engined b-pipe at that, flowing to 8k. the mr2 has a shorter pipe and much lower rev range.

plus a well built b-pipe and header sounds SO much better than an ssac/chinese knockoff.

[honda_bar]

another vote for sticky, thanks. Funny that this post just came up, another board member and I were JUST talking about this... I do have a question for you though. Since quite a few of us live in Cali, we are going to be running into problems with the headers/ cat aspect. Do you have any advice on this problem? I want to do the mild upgrade, but fear that smog is going to kick my *@$ on this. Unless I take off the stuff and replace it for smog... Is this my only option? Thanks..

[mrturrari]

The cams will still give you a gain even without the header and still pass a sniffer as long as everything else is working properly. You could also try porting the exhaust manifold although cast iron is tough stuff. Can you have a cat back exhaust at least in CA? Also do they look behind the carpet in the trunk? If not then a piggyback and some tuning could help you too and you could even try running some performance cams like the 763 grind with larger injectors. They wouldn't be able to tell if you over clock the ECU to raise your red line either. You won't be able to hit the numbers you could with a header but you will be able to make some gains. I think Pressure2 posted a dyno a few months ago showing some decent gains with just the 294 cams. 30rwhp more at red line and a nice increase at peak. I don't believe the car had a header on it but I could be wrong.