nate24740

i found this on another post has it been done or can it be done. sounds like a real good idea


I have this theroy that might help some people. Im planning a build this winter. im going to get a D17A2 from a wrecker tear it down and put higher compression D17A7 pistons in it. What do you guys think? specs on both are as follows...

D17A2

VTEC-E
• Found in:
o 2001-2005 Honda Civic EX
• Displacement : 1668 cm3
• Bore and Stroke : 74.98 mm X 94.4 mm
• Compression : 9.9:1
• Power : 127 hp @ 6300 rpm
• Torque 114 ft-lb @ 4400 rpm
• Valvetrain : SOHC VTEC-E
• Fuel Control : OBD-2 MPFI

D17A7

Found in:
o 2004-2005 Honda Civic GX
o Uses CNG (Compressed Natural Gas)
• Displacement : 1668 cm3
• Bore and Stroke : 75 mm X 94.4 mm
• Compression : 12.5:1
• Power : 100 @ 6100 rpm
• Torque 98 ft-lb @ 4000 rpm
• Valvetrain : SOHC
• Fuel Control : OBD-2 MPFI

I would need to mill the A2 Block 0.2mm to fit the pistons correct? and once back together H/I/E and stage one cam.

I dont know what would happen or even if it is worth it. What do you all think? i think its a theroy.

I know the Natural Gas pistons will work on a gas engine becauswe those are the spec'd pistons used in the d17 stroker. google it im too lazy to link it.

but yeah i think its something new and different for the d17 and could just be crazy enough to work to boost compression and overall power and torque. all controlled by an aem ems of course...

and?

toyomatt84

iTrader: (1)

If you got the connecting rods from the D17A7 as well, I would say it's a possible swap. Just make sure to check for clearances from piston dome to the valves.

Boilermaker1

I wanna say its been tried before, but I dont recall a serious attempt ever being made at it.
I'd use a K-pro to run it rather than an EMS, but thats me.
Use A7 rods... they're shot-peened and therefore stronger. I dont see why it wont work, the issue is going to be whether or not you can make it run on 93 octane without a major risk of pre-ignition.... if you have access to E85, convert the whole fuel system and use it... its the equivalent of 100-105 octane.

bomerman19

you will not have to mill the deck to make the it fit, and on a stock cam it will clear the gx pistons have reliefs cut into them. the head and cam on the gx is the exact same as the D17A1.

the only time anyone has used the gx pistons was on a d16 with d17 bottom end thrown into it. the car was meant to be used for honda challenge but then got mothballed for an integra with a k-swap and s2k pistons wich is now not allowed in honda challenge. the had also milled the deck and cold welded the combustion chamber putting the compression at something like 13.2 to 1. It should run on 93 octane but I wouldn't use anything but k-pro to make it run cause it is not going to want to idle for **** with out k-pro.

Oh and your stats are wrong the A2 and the gx motor both have the same bore and stroke.

I have a block waiting for gx pistons to drop in but I need money

nate24740

so far i like what i have heard keep it coming. oh yeah!! should i bullet proof the block and head or do you think that i can just leave it stock. and if it were to detinate at the 12.5:1 is the any way to lower compression say milling the pistons down a little or using one of the low compression rods. idk ??????

Curiouz_G

if the stock d17 block can handle 490whp, it can handle what youre throwing at it.

Boilermaker1

there's no such thing as a low compression rod. Compression ratio is a measure of volume from bottom dead center to top dead center.
I wouldnt go milling cast pistons down, You're messing with stock parts which are comparatively cheap vs. their aftermarket equivalents for this motor. If you're seriously worried, call Wiseco or Race Engineering and see if someone will run you a set of one off 11:1s.
If it starts detonating, then you need more tuning. You can do a lot with the mapping before you need to go to 100 octane.

Boilermaker1

Ehhh.... if its tuned, then it'll take it. If the motor starts pinging.... you'll crack a sleeve in no time.
Andy's car was rediculously well tuned, and running on C16 when he made that.

bomerman19

ahh you beat me to it justin on the rods.lol

wiseco will make custom pistons all the way up to something like 14.2 to 1 compression it's like an extra $75 to make them to custom specs. I believe metal viper on cf and 7thgen has a set of 12.5 to one but they are over bored a little much for me

and the block and head gasket still held when he miss shifted at 8000 rpms down into second from third. slightly scored the sleeves.

I would get arp head studs if you went with 12.5 comp pistons cause 12.5 when I ran the calculations it generated a lot of pressure it should be equivalent to about 6, 6.5 pounds of boost and you are kind of right on that edge were the head starts to lift from all the pressure. also I would replace the rod bolts with arp rod bolts if I am replacing the pistons cause you are already in there and they cost all of 35 dollars for a whole set.

Curiouz_G

oh you would justin, you would

katzenjammer84

I'd love to see numbers from this.

bomerman19

^me too lol

shifty35

The GX piston code is PMS. They are on national backorder, and have been for a while. Good luck getting a set.

bomerman19

really! I swear to god it' always something first its cone rings in the transmission then its honda fit diff bolts now the gx piston. Honestly I can't say that I am surprised there is only about 5 of those motors listed in the country in junkyards. hmm well then the only way to get a set is to order them and wait I guess I will talk to some of my honda connections either tomorrow or next week, and see what they can do. I do know that their is one set of rods in the warehouse in Detroit last I checked

nate24740

i would like to see what i can get out of the under dog d17a2. and have been asking questions on here about the d17a7 pistions and if they will work. so now i want to ask what kind of a gain i might get out of raising the compression to 11.5:1 or like on the d17a7 12.5:1 on this motor.

Curiouz_G

no ones really done that before. you might be the first afaik. pauls doing that, as soon as he gets some funds ahah

20-EM2-05

I thought that the D17A2 is just Vtec not Vtec-E?
But that sounds like a nice build though.

bomerman19

d17a2 is considered v-tec e it is not like normal v-tec that open up both intake and exhaust valves it only opens up the valves on the intake side.

According to compression calculators you should get all of 12 hp but I don't think that is right at all.

I checked a couple days ago with honda their are only 3 std bore gx pistons in the country there at a dealership in cali and there are only 2 of the .025 overbore pistons in the country. So if anyone has just one gx std bore piston laying around let me know.

And the other problem is that they are not on back order yet some has to first buy the 3 piston and then honda has to recognize that oh we don't have this part. get in contact with the company that makes it and then wait for them to make it. so your looking at a minimum of 2 months possibly longer to get one piston. so I think I am going to put off this project for a bit. I encourage any one else to go for it and try it but I will say this you will need k-pro to get it to run right and you may have to clay the motor if you want to run a crower cam.

TKDTim1226

The only issue I take with this is I've heard that all SOHC VTEC motors only work on the intake side.
http://www.civicforums.com/forums/7-...explained.html
This link is from another forum (so some people may not take it as authentic enough), but I've heard the same thing from very reputable sources like Honda Tuning Magazine and many other forum sites as well. If you can show me proof of a motor that is SOHC and runs on both intake and exhaust, I would greatly appreciate it.

nate24740

first were or how do you get the calculations.

second if you add the stage two cam with the high compression pistons won't they help each other out as far as over all horsepower and with k-pro are there horsepower gains there also.

TKDTim1226

I found this article. It might be of help to you. Or it might not. Aparently somebody had this idea before, just with a d16.
http://www.hondatuningmagazine.com/t...6a6/index.html

Curiouz_G

you just relayed what he said. bomerman just stated that vtec-e will open only on the intake side.

bomerman19

this would be run with the stage 2 or stage 3 cam on my car it is hard to calculate with cams so you dyno with the cam and use that as your base power before you up the compression but when it comes down to you will never know for sure unless you actually try it. there are compression calculators on line for figuring out HP and Tq just google it and you will come up with a bunch.

other thing is with the bigger cam the valves open up more so you probably should clay the block before you fully build the whole thing just to be safe.