7AG - a few questions

[eightsixboy]

I think you misunderstood me. My post was in response to you sounding disappointed that a stock bigport head on a 7A with a small bump in compression made only mildly more power than a stock bigport. It sounds like you expect the 7A to give you a big bump up in power with nothing else done to support it. It wont. If you want to make significantly more power than stock (if you want a number, then lets say 100 or more kw at the wheels) then the only way that is going to happen is with cams, compression, and an ecu.

I understand what you are saying, I'm saying it doesn't make sense that a motor with higher comp then smallport, with smallport pistons, and a full rebuild only makes about the same as a stock smallport. You would think the higher comp + more cc would give it more power just from that alone.

I have seen a 7AG with cams, full standalone and heaps of work done, but it only made around 120rwkw.

[xero]

i have a built smallport 4ag with 'only' 1600cc's and i make 130rwkw. whats your point?

who knows why or if these builds you are basing your facts off are optimised or not, if they are running cams, head work, a decent exhaust or intake system, could be the dyno operator is a potato and cant tune for shit or the engine itself has been slapped together creating more problems than solving.

then again just because "it only makes 82rwkw, it must be slow/shit/bad at life". i have made similar power before and while it isnt much on paper, the area under the curve and real world power delivery (through a dead standard 350k km old T50 and factory T-series rear end with 4.3 final ratio) made it harder for more powerful cars to catch, especially in corners.

[eightsixboy]

i have a built smallport 4ag with 'only' 1600cc's and i make 130rwkw. whats your point?

who knows why or if these builds you are basing your facts off are optimised or not, if they are running cams, head work, a decent exhaust or intake system, could be the dyno operator is a potato and cant tune for shit or the engine itself has been slapped together creating more problems than solving.

then again just because "it only makes 82rwkw, it must be slow/shit/bad at life". i have made similar power before and while it isnt much on paper, the area under the curve and real world power delivery (through a dead standard 350k km old T50 and factory T-series rear end with 4.3 final ratio) made it harder for more powerful cars to catch, especially in corners.

I never said it would be slow, I think your reading to much into my comment. I was just replying to the comment "if you want decent power". It all comes down to what you consider "decent" power.

I'd be stoked if I could get 130 wheel kw out of my smallport, it would be more then enough for me to be honest.

I was just saying that it seemed a bit odd that most 7AG builds I have seen don't push big numbers, in comparison to similarly modded smallports, it doesn't mean it will be slow at all. I'm just wondering for what I want to do, and considering the money to build a half decent and reliable 7AG if modding the smallport is actually a better option. The link I posted with the guy selling his 7AG had a huge build thread on his car on ae86drivingclub, I would consider his 7AG to be built very well, just limited by stock ecu, cams etc. I did find it odd that he never mentioned the torque figure, and when asked he kinda skirted the subject.

[trdee]

I understand what you are saying, I'm saying it doesn't make sense that a motor with higher comp then smallport, with smallport pistons, and a full rebuild on a bigport head with stock cams and stock management only makes about the same as a stock smallport. You would think the higher comp + more cc would give it more power just from that alone.

I have fixed your post above to include the part which you are missing in your equation.

As I have said a number of times now; throwing 200cc and a small bump in compression at a 4AG isnt suddenly going to turn it into a fire breather. Assuming the dyno figures are accurate, that engine has picked up roughly 10kw over a good condition bigport 4AGE. That is fairly reasonable IMO considering it is being held back by the other factors I have mentioned.

[oldeskewltoy]

[eightsixboy]

I have fixed your post above to include the part which you are missing in your equation.

As I have said a number of times now; throwing 200cc and a small bump in compression at a 4AG isnt suddenly going to turn it into a fire breather. Assuming the dyno figures are accurate, that engine has picked up roughly 10kw over a good condition bigport 4AGE. That is fairly reasonable IMO considering it is being held back by the other factors I have mentioned.

Point taken.

I don't know why everyone is taking this stuff personally, geez :/ All I wanted to know was if I could use the stock 7A pistons with decent results and now people are getting butthurt becuase I was just a little disappointed that some guys go through not exactly a "cheap build" and the gains are minimal. BUT as I said, I couldn't find any proper dyno figures for 7AG's that showed torque, which is the reason for doing a 7AG.

Honestly I don't know what path to take with my smallport now. Realistically I would be happy with around 80-85kw but I'm more concerned with an increase in torque or a more usable power band. The cost of building a decent 7AG while using stock ecu etc would pay for some cams and a standalone for the 4AG.

[trdee]

Not taking anything personally (am I yelling at anyone?), just trying to help you adjust your expectations so you don't get disappointed down the track

OST - lol wut

[xero]

Point taken.

I don't know why everyone is taking this stuff personally, geez :/ All I wanted to know was if I could use the stock 7A pistons with decent results and now people are getting butthurt becuase I was just a little disappointed that some guys go through not exactly a "cheap build" and the gains are minimal. BUT as I said, I couldn't find any proper dyno figures for 7AG's that showed torque, which is the reason for doing a 7AG.

Honestly I don't know what path to take with my smallport now. Realistically I would be happy with around 80-85kw but I'm more concerned with an increase in torque or a more usable power band. The cost of building a decent 7AG while using stock ecu etc would pay for some cams and a standalone for the 4AG.

you keep saying torque. i do not think this word means what you think it means.

so by torque do you want that push in the back feeling you get from say a very large engine (lets say a V8 or turbo), or the stump pulling effortless feeling from near idle like a diesel engine?
with an N/A 4AG or 7AG you wont really get that feeling at all, simply because its a small capacity and doesnt have much to begin with. what they do have is the ability to rev and rev up quickly. so you wont have the torque you want but you can gear it short to make up for it and use what little you have.

if you want the car to be quicker with a good power band (IE more point and squirt and pick up speed quickly) on mostly stock smallport this is what you will need to do:
programmable ECU
cams (at least a 264deg cam)
decent extractors and exhaust system
lightweight flywheel
*6sp box (*optional but worth it)

you will net between 85-95wkw, with an 8500rpm rev limit (max limit), have a good spread of power that is usable almost everywhere, and it will feel like you have increased torque (you wont have, just the shorter gearing will get it moving quicker).

[oldeskewltoy]

compression... compression... compression!

A TVIS 4AGEC (the "C" = catalyst equipped) engine in 80% of the world planted 112-115hp, it uses 9.4 to 1 compression. In Singapore, and some areas of Europe (none emissions areas) they got 4AGE engines, without cats. These engines were fitted with 10 to 1 pistons and they made 125hp.

compression... compression... compression!

The smallport engine was fitted with more compression(10.3), and made 130hp. So the difference is 5hp, and 3/10 of a point of compression. Considering 6/10 of a point bump gained 10-13hp, another 3/10 should net another 5

It is fair to say that peak power in a smallport and largeport would be very close to equal while both have equal compression.

So back to your 7AGE... with a static compression of 10.7 to 1, stock cams, stock management, you should be close to 105-110 kilowatts

[eightsixboy]

you keep saying torque. i do not think this word means what you think it means.

so by torque do you want that push in the back feeling you get from say a very large engine (lets say a V8 or turbo), or the stump pulling effortless feeling from near idle like a diesel engine?
with an N/A 4AG or 7AG you wont really get that feeling at all, simply because its a small capacity and doesnt have much to begin with. what they do have is the ability to rev and rev up quickly. so you wont have the torque you want but you can gear it short to make up for it and use what little you have.

if you want the car to be quicker with a good power band (IE more point and squirt and pick up speed quickly) on mostly stock smallport this is what you will need to do:
programmable ECU
cams (at least a 264deg cam)
decent extractors and exhaust system
lightweight flywheel
*6sp box (*optional but worth it)

you will net between 85-95wkw, with an 8500rpm rev limit (max limit), have a good spread of power that is usable almost everywhere, and it will feel like you have increased torque (you wont have, just the shorter gearing will get it moving quicker).

When I say "Torque" I guess I am talking about having power without revving the guts out of it, so yes in a way like "stump pulling effortlessly" feeling.

To be honest the smallport has decent torque down low at around 1/4-1/2 throttle for a 1.6ltre, it feels quick and nippy around back streets, its only if you really need to boogy and you plant your foot that you don't go anywhere till after 5k or so, so your either shifting back to 1st or waiting waiting waiting until you hit the power band. I'm not talking about flooring it at like 2k and expecting V8 torque or anything stupid like that, but if your sitting around 3.5-4k you really don't have the torque to go anywhere.

Having owned a S/C aw11 in the past I remember just how much quicker it felt, even though it wasn't necessarily making a lot more power, just having that low down torque was awesome.

My spare smallport already has .8mm headgasket and slight head skim, so I could just put some cams in that and swap the motor over.

[eightsixboy]

Not taking anything personally (am I yelling at anyone?), just trying to help you adjust your expectations so you don't get disappointed down the track

OST - lol wut

All good, I just don't want anyone to think I'm bagging 4AG's or saying that some 7AG builds are crap. I guess just for time and $$$ spent on building a 7AG I would want to at least gain a sizable torque increase over a 4AG, but then again I guess 200cc isn't a huge increase in capacity.