Ok,
So I have an extra block and every bolt on one can buy other then an I.M simply because I'm not set on the weapon-r. I have a Flash Pro and dyno at 125 whp. I have no a/c or cat and a 55mm tb( note the r18 civic engine from 07 uses the same tb but with a 55mm butterfly over a 50 mm they cost about $65 direct bolt on). Anyone can buy a L15a7 for about $1000 used and have it shipped for that price. I already have a fresh L15a so now all I need is the L15a7. My plan is to used the L15a block and crank with the L15a7 piston and rod since they are a better design and I believe the L15a7 has a bigger cc then the L15a so using L15a7 piston should net me a high comp. I will use the rocker arm and cam for the L15a7 into the L15a head to lose 12v/16v vtec to gain really vtec without the integrated header. Hopefully this will create a real L15a Vtec.

I believe from research that the L15a rocker arm is the same that is used on the L15a LEA CRZ engine which in Japan Spoon Swaped the Rocker Arm and Cam and gain so real hp and were reving to 7500. (now who knows the true mods completed on this car *Spoon CRZ*) But I think this is a cheaper option for GD3 owners to gain N/A HP. If I can get the intake manifold to work off of the L15a7 on the L15a head then I'll try to pick up a HPD Plenum from F1.

Also please I know the L15a or L15a7 is not going to be a super hp creating engine; I race in a spec class so I can only mod my car n/a. No it is not SCCA and i'm not cheating the class is small bore engine smaller then 1.6 limit and no vtec engine other then then L15a. The fast car in the class now is a 90 miata and 92 d16 non vtec civic.

'Any insight on this project would be helpful.

 

Sounds interesting.

From here:
Honda L-Series SOHC i-VTEC Engines for the new GD Honda Fit/Jazz

The new style L13A use iVTEC with a similar rocker design as the old L15A1, so that might be something to look into if that ends up being a problem. Let us know how it goes.

 

Well for you GE8 guy this could mean losing the intergraded header as well but this is only if the L15a head will match up with the new L15a7 block which has the new dual passage water jacket. If this works then I will simply install the L15a head on the L15a7 block with the L15a7 rocker and cam

 

Yes i've always read that was the problem with mating the a7 head with the a1 block, the cooling passages. That's why I thought your valvetrain swap was an interesting solution and would keep the integrated exhaust manifold out of the equation. I don't know if the L15a7 valvetrain will swap into the a1 head? They look very different as far as how the cam is bolted to the head just by looking at pictures?

 

Is the Vtec engagement solenoid compatible with the I Vtec cam and rockers? Then what are you going to the Vtec engagement point. with the GD ECM it's at 2500 and with the GE it's 5500?

 

VTEC engagement is referenced by MAP and RPM on both GD and GE.

Depending on MAP the GD will activate the solenoid between 2400-3500rpm:

 

Wow, I have been away for too long!

I was looking into the SAME general valve train swap till funds/job ran out.

Try contacting user Lyon[Nightroad] as he had a full upper rotating assembly out of a GE for sale (Cam, gear, rockers and all.)

Would love to see where you get with this! What intake and exhaust setup are you running? I have a Weapon R IM that has been braced, but I can't use it in my SCCA class. Nor the 55mm throttle body sadly.

My current bolt on/exhaust combo tuned on FlashPro is right around 110 at the wheels calculated by Dyno AND ET, weight and trap speeds

I would LOVE to compare notes and see where you found the extra 15whp, and I doubt its all in the TB...

 

Very interesting ideas, I'm also interested in building the L15 N/A for the occasional drag racing. My goal is 15s N/A on a budget!

OP do you also have a lightweight flywheel? My focus will be on making everything as lightweight as possible.

 

I ran a 16.6 with my car on about 1/8 tank of fuel, fresh plugs at the time, and already had a few tanks of fuel running 93 for the ecu to relearn after resetting the ecu at the time.

This is on a GE8

I am VERY confident a GD3 with flashpro can attain status in teh 15 second club with boltons and a mild cam upgrade. after your vtec kicks in, it simply acts like an oldschool honda nonvtec, and Ive personally gotten a d15b7 to nearly 150whp and in the 15s with an automatic in a del sol.


Your biggest challenge I think is massaging the head if you get a bigger cam.

De-shrouding the valves will produce a significant gain in the high rpms. I do not know how bad the GD3/L15A1 heads are, Ive never had the opportunity to view it in person

 

Problem with the L15A head (GD) is that it has VERY thin walls and after any kind of porting work you can have cooling problems abd or hot spots : /

I'm in the 16.5's with my GD, but I'm focused on AutoX, so things like my -3.5° of front camber do not help LOL

 

I remember on the skunk2 fit the didn't really poet it as much as clean it up and smooth it out. You can do some light porting. TP have you fully blue printed your engine yet? I am assuming that is allowed in the class you run in.

 

I had the YouTube link for "How to Port a Fit Head by Skunk2 somewhere vut can't find it this second. Essentially though yea, cleanup is about it.

Sadly I cannot do any internal stuff in my current class. Everything before the throttle body and almost anything after the exhaust ports (have to retain a hi flow type cat) is free.

 

it has enough material to deshroud a bit. Even if you open it up 1 or 2mm around the valve on the outer edges of cylinder, it still translates into a reasonable and worthwhile gain. You can also grab a spare head and have a talented shop weld in extra material if necessary. extra head means learning curve! Lets see what the L15A1 head has to offer!!

This is what gave my ol d15 the most out of its headwork. I saw my AFRs rocket to around 14.5 in the upper 8ks after doing this and port-matching the exhaust, and creating a step on the intake side to keep the air from "bouncing" out.

When I did my street tuning, I always shot for a high 12 AFR, with pretty heavy throttle enrichment. Never hurt a motor!

 

I would think that having the carat factory specs would be allowed in a "stock class" . I think that a solid cleanup of the ports and taking even a little meat off combined with the Hondata and some others bottom changes would yield some solid results.

 

so did anyone actually buy the parts to try and swap this around?

I bought a spare l15a for a turbo build and would love to get some l15a7 parts to start seeing what matches up and what doesnt.

 

I believe there was an issue with the water jackets between the new head and the old l15 block. not sure what thread I read that in.

 

I recall the same as Stevens24, but that was for a direct head swap.

So far, no one I know has tried to swap the GE valve train to a GD head...

 

Well if I can find a GE valve train I would kindly do this and get to a dyno to see if it makes a difference in the power curve.

 

bumping an old thread.

For all those interested, the l15a7 valve train will not bolt into an l15a1 head. the cam caps are solid pieces cast into the head so they are not interchangeable.

 

This might sound silly, not sure if transmission of L15A4 i-DSI fits L15A1, L15A4 being 88 PS produces Torque: 128 N·m (94 lb·ft) @ 2,700 rpm, if fitted to L15A1 more torque can be generated.
I dough if those transmission fit each other if yes logically let the the torque converters do the job.