Honda D Series Forum banner

1 - 17 of 17 Posts

·
Registered
93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
Joined
·
415 Posts
Discussion Starter · #1 ·
If you arent familiar with Thompson stroke motors its basically a hybrid power/economy build, typically they would use a roots and vane type supercharger that builds boost at low rpm easily, then hang the intake valve open upto 21 degrees into the upward compression stroke, thus reducing the amount of power needed to compress the intake charge by up to 30% while retaining volumetric efficiency at whatever atmospheric pressure you could get the motor to handle. I played with this long ago and far away with other peoples money, I still service some of those builds today.

So I've been thinking of taking those general principles of keeping the intake charge in the cylinder with boost while hanging intake valve open to reduce compression losses, thus yielding greater power, efficiency, and possibly lower emissions. As I love my D series I thought id start experiments on that platform, though K series makes more sense, I just don't like the bore/stroke and vsa/displacement ratios and feel they may need extra attention to internal geometry.

I'll be going at this in stages, stage 1 is nearly complete, just details to button up and mk2 will be logging data for me. I'll get baseline mpg and whp measurements, after some tuning of course, going to be a crash course in the finer nuances of smanager as I get her dialed in.

Stage 2 will be flex fuel conversion and tuning, I may also convert to COP ignition at this time with cdi planned upgrade for boost, on deck for that conversion is a 80 psi max 260lph e-85 compliant fuel pump, adjustable rising rate fpr and 510cc e-85 injectors. Some fuel line upgrades as well I think, I need the fuel pressure as low as 34 psi when running 91 octane, and it seems the regulators im looking at need a 5/16 line on return to flow enough with the pump i have chosen.

Stage 3 will add boost on the stock cam, probably a .45 trim ceramic ball bearing t3 with .48 ar housing and the second step turbine wheel (hard to find), the intercooler needs to be smaller or response is lost, so probably an audi a4 unit. At this point I'll log mpg and whp again, then I'll dial in the tune and do it again. No idea how e-85 tuning is going to work out so I need a baseline before the next stage so I can extrapolate.

Stage 4 should see gains in whp and mileage, ill have a cam ground where the intake valves in vtec hang open a certain amount of crank movement, they will close approximately 10° crank rotation before the instance of 90° which itself may need adjusted via offset wrist pins and main bearing bore alignment, once turbo starts to spool vtec lobe kicks in and Thompson strokes the motor, reducing the amount of power lost compressing the next cylinder to fire each time by up to 30%.

Stage 5 will be a custom geared trans built to capitalize on the specific power curve of the resulting Thompson stroke turbo engine. That's going to need a bigger brain than mine and I hope bense and tranzex feel free to chime in by that point.
 

·
Registered
Joined
·
6,821 Posts
so basically you want to rebuild a factory honda R18 style setup? Maybe I have been sipping some juice tonight, but kinda seems the path you want.

Honda did an awesome job on the R18, and a small supercharger on one would kinda seem to fit your goals


Toyota did a similar trick with the 2nd gen prius 1.5 motors. de-compresses at idle and low rpm for ease of motion. Yeah, it lacks power, but the engine barely uses any fuel idling even cold in comparison to a normal setup
 

·
Registered
93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
Joined
·
415 Posts
Discussion Starter · #3 ·
The R may well fit too, but yuck to every chassis I could afford to build 🤢 the ratios however are near perfect, heat soak in the head from a turbo may cause driveability issues though. Im thinking go a step further than the traditional super charger, with the ability to alter cam timing or entire lobes it should be feasible to run a 9.4:1 or so until spool starts, then vtec lobe drops static compression to around 8.1:1 and getting the start of compression building to much closer to the instance of 90°, with pwm boost control dialed in to generate ideal dynamic compression ratio for conditions... its all just possibilities so far, thus the thinking about it. The R is a real possibility as the idea progresses.
 

·
Registered
Joined
·
6,821 Posts
heat soak in the head?

What are you on about?
 

·
Registered
93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
Joined
·
415 Posts
Discussion Starter · #5 ·
It seems to me the exhaust side of the r head would have heat issues running a small turbo with higher than normal drive pressure. Could and may likely be my imagination , I havent ever really played with the r. I think I've put an intake on one and a cat back system on another, and one head job, so next to no experience with them.
 

·
Registered
Joined
·
6,821 Posts
A small turbo is going to flow much easier than a complete stock R18 exhaust.

R18 fits nicely into the EG/EK chassis with minimal effort
 

·
Registered
93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
Joined
·
415 Posts
Discussion Starter · #7 ·
CA smog isint going to let me drop in an r18 without 6 months worth of paperwork, not having that paperwork done results in an impound fee and destruction of the car now. But there are carb legal routes for me to build a d into a Thompson stroke. I may buy a beater to test on the r with later, with the intention of ditching the chassis after everything is sorted and carb exemption is ready. More importantly I have much more experience and more sources for spare parts with the d platform, figuring out fueling and injector timing to make this work best will be enough on my plate without scrambling to learn a new platform I think.
 

·
Registered
Joined
·
6,821 Posts
well, here is something worth checking into. The d16y8 valvetrain can be swapped into the vtec d17 head that normally has 3 valve low, 4valve high mode with a switch around 2500 rpms.


What about trying to put the D17 vtec valvetrain into a d16y8 head, setting valve lash on the one valve so it drags the valve open ever so slightly, then you simply enable the vtec-e to 4 valve mode for extra power? That way, you only have 1 of 4 valves in each cylinder slightly open, and the turbo can make up the compression/velocity loss. With proepr oil (0w-40, or 20w-50) you will always have enough pressure to ensure the pin comes out, and the d17 valvetrain is built around low pressure activation. I bet you could get it to operate as little as 1800 rpm or so.


Just spit balling here!

EDIT btw, the d17 cams all have a cam slot that can potentially accept a distributor, plus since you would be stuck using the d17 camgear, you now have a location for a cam sensor directly. No more relying on 20+ year old oem distributors for the proepr 4-1 wheel! You do loose the ramp, but gain precise cylinder position.
 
  • Like
Reactions: slo_eg8

·
Registered
93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
Joined
·
415 Posts
Discussion Starter · #9 ·
Thats actually a very good idea, COP ignition would be easy that way, and thats a roller valve train further reducing friction. I'll have to find an a2 head to cannibalize, I do have a y8 head sitting, though it needs a couple exhaust valves.
 

·
Registered
93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
Joined
·
415 Posts
Discussion Starter · #10 ·
I wonder if i could scrounge up a 3 step vtec head?🤨 Stroke it to 1.7, run a mostly stock single intake lobe, a mild Thompson stroke lobe on 2nd valve for low to medium boost (3-5 psi) and a further retarded higher duration vtec lobe for higher boost pressures. That would take care of all my d series bucket lists in one shot😃

A ported z6 oil pump should be able to operate that reliably as low as 1700rpm with my favorite 10w30 synthetic oil with 20% synthetic Lucas oil additive to bolster surface tension. The increased displacement would no doubt help low end torque and turbo spool, making Thompson stroke effects kick in that much sooner, and having a third option for high load situations would undoubtedly help in making it carb compliant. With a little elbow grease and a LOT of tuning I might turn this into something.

They are going to want some sort of carbon canister for blow off i bet😢
 

·
Registered
93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
Joined
·
415 Posts
Discussion Starter · #12 ·
Slight issues finding a 3 stage head, waiting on rods currently to start notching the block and girdle, searching for an appropriate turbo, intercooler, ect.
I do have my backup Z6 head apart, getting ready to port match a spare intake manifold in case I cant find a 3 stage head that isn't cracked. I also need to source an Hx 3.73 geared s40 trans.
Hondata ecu from xenocron should be here in the next couple weeks so I can start getting swapped over to flex fuel and dialed in.
 

·
Registered
93 Civic HB SI
Joined
·
1,317 Posts
Slight issues finding a 3 stage head, waiting on rods currently to start notching the block and girdle, searching for an appropriate turbo, intercooler, ect.
I do have my backup Z6 head apart, getting ready to port match a spare intake manifold in case I cant find a 3 stage head that isn't cracked. I also need to source an Hx 3.73 geared s40 trans.
Hondata ecu from xenocron should be here in the next couple weeks so I can start getting swapped over to flex fuel and dialed in.
Dude, progress! Your holding out haha. Down for pics!
 

·
Registered
93 Civic HB SI
Joined
·
1,317 Posts
No idea how e-85 tuning is going to work out so I need a baseline before the next stage so I can extrapolate.
Dont worry about ignition timing too much, stock is fine, scaled for boost. Feel free to advance to your hearts content once on the dyno, and find your torque sweet spots lol. With high alcohol concentration, 80+%, and a reasonable/not too crazy max dynamic compression ratio target (no 14:1 static comp with 40lbs of boost haha), youll never really need to worry about detonation. On E with reasonable boost, most of the time you'll safely reach MEP, and safely overshoot it, before you ever see knock. E is sweet lol.

Still, have your det can listening while you creep up the timing if boost is high.

To get it running on E pretty well, add 20% to your base fuel table using the flex modifiers in SManager.

Then simply tune on the lambda scale using your wideband. Lambda 1.00 is always lambda 1.00, regardless of fuel type :)
 

·
Registered
93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
Joined
·
415 Posts
Discussion Starter · #15 ·
Dont worry about ignition timing too much, stock is fine, scaled for boost. Feel free to advance to your hearts content once on the dyno, and find your torque sweet spots lol. With high alcohol concentration, 80+%, and a reasonable/not too crazy max dynamic compression ratio target (no 14:1 static comp with 40lbs of boost haha), youll never really need to worry about detonation. On E with reasonable boost, most of the time you'll safely reach MEP, and safely overshoot it, before you ever see knock. E is sweet lol.

Still, have your det can listening while you creep up the timing if boost is high.

To get it running on E pretty well, add 20% to your base fuel table using the flex modifiers in SManager.

Then simply tune on the lambda scale using your wideband. Lambda 1.00 is always lambda 1.00, regardless of fuel type :)
Static compression will be roughly 9:1, dynamic will depend on what lobe its running and what load its at, so 1 valve mode would likely run until 5 psi, about a 12:1 dynamic, when the second valve opens and stays open til 20°ABDC the boost limit will be somewhere around 12 psi to reach a maximum of roughly 12.5:1 dynamic, on the high lobe with both valves hanging open until somewhere between 28 and 32°ABDC boost could go as high as 28psi before reaching 13.5:1. once I get the pistons, rods, crank done ill start degreeing in the cam profiles to see exactly when ivca needs to be to effectively destroke to 1.55L (2 valve) and 1.4L (high lobe).
 

·
Registered
93 Civic HB SI
Joined
·
1,317 Posts
Static compression will be roughly 9:1, dynamic will depend on what lobe its running and what load its at, so 1 valve mode would likely run until 5 psi, about a 12:1 dynamic, when the second valve opens and stays open til 20°ABDC the boost limit will be somewhere around 12 psi to reach a maximum of roughly 12.5:1 dynamic, on the high lobe with both valves hanging open until somewhere between 28 and 32°ABDC boost could go as high as 28psi before reaching 13.5:1. once I get the pistons, rods, crank done ill start degreeing in the cam profiles to see exactly when ivca needs to be to effectively destroke to 1.55L (2 valve) and 1.4L (high lobe).
Oh yeah, youll have fun on E :) shouldnt ever det under normal circumstances!
 

·
Registered
93 4d lx, z6,ported, port matched, compression bumped, balanced, manual swap
Joined
·
415 Posts
Discussion Starter · #17 ·
Wife is on me about the A/C, tint, and probably the body and paint, once again my toys get put on the back burner😞
 
1 - 17 of 17 Posts
Top