Best way to get torque? (N/A)

[Chip-mk1]

Will you explain this further please

Back pressure means the manifold pressure in the exhaust manifold essentially (well its the exhaust ports that really matter but same thing effectively)


I did explain it a bit further up.

Back pressure is always bad for all 4 stroke engines but on a turbo you have no choice but to have some as the turbo relies on a pressure differential before and after it.

Gas speed increase from a smaller exhaust pipe is good for low down torque on an n/a engine. But that's about generating negative back pressure at the end of the exhaust stroke. It's not about having positive back pressure. That's always a bad thing.

But to go into a little more detail "back pressure" as a good thing at certain points of the cycle on 2 stroke engines for efficiency as there is a point where both inlet and outlet are open at once for quite a while and it can result in the gasses going straight through otherwise, as a result its got into the phrases that people bandy about as if its relevant on all engines, and it just isnt.

On a N/A 4 stroke engine, there is no point in the cycle that it is ever beneficial to have back pressure.
(slight exception would be if you ever tried to tune the exhaust of an engine on massively overlapped cams to be best at low rpm but thats just not something anyone would ever do as you wouldnt use those cams if low rpm was the issue)

 

[Martin_172]

Thats more gain than I would expect TBH, do you have the two rolling road printouts for comparison? (just to be nosey at intake temps and stuff I mean)

sorry for the late reply just saw this, of course the usual RR issues can affect the figures both runs were done about a year apart, on the same rollers, with mainly the same "other" cars there who ran pretty consistent year to year, so that gave me a reasonably accurate figure of what I gained, of course its hardly 100% accurate but in the interest of seing the benefit my mods gained, I was happy!

Standard (worth noting on the day most 172s were running the usual 165hp, this was a strong one as standard)....

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modified.....


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[Chip-mk1]

Interesting graphs, you are quoting the wrong figure by the way though, the corrected engine power afterwards is 184 not 188. But in terms of gains your before figure was really 170 anyway so still the same gap between them roughly.
The reason to use the corrected figure is that 188 is what it will do on a cold day, the 184 is what the dyno estimates it will do on a "standard" day, if you run yours on a hot day in theory it will make about 180 but then should still correct back to the same 184, so thats why thats the figure we use for comparison as its the only meaningful one.

But that applies to both graphs, so certainly a noticeable gain in very similar conditions though on your before and after.

Little confused as to why it would register over 10% less loss on the second graph though, that seems quite a big variation, but no matter what way you look at the figures, I dont think there can be any doubt you have made a very significant increase with the mods you have

Bet that goes really well

 

[Martin_172]

ah right always wondered what the corrected figure was for.

it went really well that car, sold it about 4 years ago though! went a lot better than my current one :dapprove:

 

[Ex-User (19928)]

Going from a 1.6 to a 172 will be a massive jump in performance. Spending the value of the car in mods will not see the same increase, or even close.

 

[Corby G]

IIRC the engine was taken from a people carrier with the hp around 120? (I know this thread is about torque) so esentially the engine is already tuned, something quite simple and weight saving would be straight through decat pipe probably pick one up for £90?

 

[Jakey92]

Going from a 1.6 to a 172 will be a massive jump in performance. Spending the value of the car in mods will not see the same increase, or even close.

Mid range feels the same til the '5k kick' but either way I don't recall saying that it would feel the same

IIRC the engine was taken from a people carrier with the hp around 120? (I know this thread is about torque) so essentially the engine is already tuned, something quite simple and weight saving would be straight through decat pipe probably pick one up for £90?

I see where your coming from.

Sounds to me like for a good daily these would just benefit from a remap unless the owner is planning to go for the all out little gains

 

[Corby G]

Totally agree, a decent induction kit straight through pipe, back box and some cams THEN the remap and the torque will follow, you'll be looking at a considerable gain, thing is with these na engines f4r and the b series from the civic etc youll throw money well down the pan for hardly a gain, a lot of people want more power power power, best advice from my perspective is weight save, and handling. If you haven't got a turbo as standard don't try find power it's not got unless you're willing to re mortgage.

 

[marky0_172]

btw , the placebo of having better throttle response after matched inlets isnt true, im 100 percent sure mine feels better even after port matching the upper and lower inlets myself ! can even prob sort out that awful factory porting done on the head at some point too, without taking the head off, aslong as no material goes south, it would be fine.

no idea whether porting inlets increased power output tho lol

 

[Mr R.]

btw , the placebo of having better throttle response after matched inlets isnt true, im 100 percent sure mine feels better even after port matching the upper and lower inlets myself ! can even prob sort out that awful factory porting done on the head at some point too, without taking the head off, aslong as no material goes south, it would be fine.

no idea whether porting inlets increased power output tho lol

It will help along with the 182 manifold, im having my head ported at the moment.

It will make more toque though.