I would expect having 2X the valves would be a pretty decent upgrade in itself as far as flow is concerned. The 1HD-T head doesn't have any real weaknesses that I'm aware of.
1HDT Cylinder Head Performance Modifications
- Thread starter Wildnlost
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I would expect having 2X the valves would be a pretty decent upgrade in itself as far as flow is concerned. The 1HD-T head doesn't have any real weaknesses that I'm aware of.
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- #62
I have modified my engine a fair amount away from stock already and with the upcoming re build I would like to make any changes that may benefit my build when the engine is apart. I have found that tinkering with this tried and proven design is both entertaining and rewarding. I am often limited by budget so maximizing what I have got is essential. Any mods I can do( possibly butchery ) in my own garage with what I,ve got is a win. When they improve power ......even better. There are many designs better than our old 2 valve design for sure.
I like playing with Machines. Building things and experimenting. This forum is a great place to bounce ideas and learn from people that have been there done that.
CHEERS everyone.
PS Back to the original question.......
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Thought yould like this. It looks like something I'd be into but perhaps with the Pistons out of the engine. He did it to address the advanced timing as you described. Look at post 17.
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In-Frame Piston Mods - Competition Diesel.Com - Bringing The BEST Together
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In-Frame Piston Mods - Competition Diesel.Com - Bringing The BEST Together
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- #64
Yes very interesting. My kind of home grown butchery. In this case it has a double effect of reducing compression and allowing for more pump advance without spraying the piston lips. According to the post spraying on the lip causes piston cracks.
Do 1HDT's like more advance 'in general '.?
As this is a daily driver and requires good cold start manners it may require a conservative approach. Instead of a die grinder maybe a hole saw to mod pistons. LOL.
I am going to be decking block. And will have to measure piston protrusion afterwards. I can flycut the piston tops to the 1 notch spec which would bump my compression up as the bowl is now smaller. Then I could machine out the first lip and gain some diameter on the bowl and maintain as much compression as possible.
Has anyone played with pump timing to know if our motors like more advance? Downside?
Hmmm... What size hole saw I wonder?
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- Thread starter
- #65
I found a few pics of my valves and head I had misfiled. The pics show the finished valves with back cuts done. Also some pics of deshrouded valves which was accomplished with a wood router and carbide burr. (more butchery). Modified fuel pin too.
@gerg has some good ideas for improving exhaust flow too. Time permitting I am going to radius the edge of the exhaust port where it meets the combustion chamber.
@gerg has some good ideas for improving exhaust flow too. Time permitting I am going to radius the edge of the exhaust port where it meets the combustion chamber.
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You won't notice to much cold start issues. Manly smokey till it gets a bit of heat. I have had it down to -5c and it still is fine. Just more smokey
How is it at -30c and beyond? -5 is fall weather here, lol.
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- #68
here is a picture of my RG500 Suzuki 1985 I have owned for 32 years . Plenty of trial and error. my third rebuild of this old girl. the engine is a 555cc, 2stroke, square 4 configuration with dual crankshafts. rotary valve induction with handbuilt everything. 290lbs and 120hp at the back wheel. stock was 345llbs and 85HP.
The exhaust pipes (3rd try) alone took over 100 hours to design and build. 27 cones per pipe. match the ports and cylinder heads to them about another 100 hours and 1 set of cylinders ported to far...in the bin. 2 sets of heads.
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- Thread starter
- #70
Used software called Bimotion to design the pipes. Pipes on a 2 stroke dictate the powerband. .Used a steel wire to establish the centrelineof the pipe on the bike. Then used Solidworks and applied the pipe design to the centreline. Unrolled the cone sections in 3D and sent them to laser cutter. Rolled the cones and tacked together. Had a friend weld up. Same parts upper and lower pipes just orientated differently. Maybe more than a 100 hours ...
Back to the job at hand.....
Just measuring piston protrusion. Highest is .018" lowest is .016". I should have been running a 1 notch gasket not a 5 notch that I installed to be safe. The difference in thickness is about .010” Considering the piston to head clearance is .025” - .030” in the service manual, that is approximately 30% of extra volume. Why did I do that?
Using the thicker gasket would reduce squish velocity considerably. Not to mention loss of compression too. Possibly leading to slow combustion, smoke, poor economy. Personally I think this is important.
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@Wildnlost that bike is pretty cool, in a crazy way!
That exhaust is the sort of stuff only a home enthusiast is likely to tackle. you'd struggle to find a workshop that didn't think you were bat**** crazy if you asked for that!
Yes, I think you is a special kind of bat**** crazy . . . .
In a good way
That exhaust is the sort of stuff only a home enthusiast is likely to tackle. you'd struggle to find a workshop that didn't think you were bat**** crazy if you asked for that!
Yes, I think you is a special kind of bat**** crazy . . . .
In a good way
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- #73
Well I have decided to machine my new pistons by enlarging the bowel... er I mean bowl diameter to 44mm from 39mm. This removes the overhanging lip on the piston but leaves the concave part of the bowl responsible for tumble.
I also am guessing that the overhang can get overheated easily by advanced timing spraying on the edge....leading to cracks. I Wont lose to much compression and a bigger hole to put the fuel into with advanced timing.
I think 44mm is very close to the late model piston bowl diameter not that that is important.
I also am guessing that the overhang can get overheated easily by advanced timing spraying on the edge....leading to cracks. I Wont lose to much compression and a bigger hole to put the fuel into with advanced timing.
I think 44mm is very close to the late model piston bowl diameter not that that is important.
You are a ballsy guy, this is an expensive test grounds, but good on you for pushing the envelope! I'm excited to see how this works out for you!
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- #75
Worst case scenario new pistons.
definition -" power to weight ratio"
....the more power you get /// the longer you wait for parts.
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- Thread starter
- #76
I have finally had time to look at my motor. So I did bore the bowls of pistons. I removed the lip on the inside edge of the rim. Went from 39mm to 44mm. The original piston lip if sprayed with fuel would heat up quickly. Advancing the pump timing puts the fuel into the cylinder when the piston is farther from the head ....earlier BTDC. Our injectors spray in a cone shape which with advanced timing would make a larger spray pattern when it hits the piston. Spray on the bowl lip .....will it cause cracks from localized heating.?.?
So logical or not I made the bowls bigger. I may cut a small concave back into the piston to create a small lip similar to the original one. There is probably a reason.
So logical or not I made the bowls bigger. I may cut a small concave back into the piston to create a small lip similar to the original one. There is probably a reason.
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- Thread starter
- #78
Finally finished up the piston bowl enlargement. Went pretty good. Could have bought later model pistons with larger bowl and saved some work. Used a wood router to finish butchering pistons.... put the chamfer on the top. There is a noticable differance in bowl diameter and bowl lip thickness. The combustion chamber volume increased by a small amount. lowering the compression a bit.Will check piston protrusion expecting .028" to .031" after plaining block .008". A 5 notch gasket will probably suit. Also painted block red.
Waiting for connecting rod small end bushings to be replaced and sized then start assembly.
Waiting for connecting rod small end bushings to be replaced and sized then start assembly.
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- Thread starter
- #79
Getting ready to drop in crank. ACL race bearings. Bearings certainly have a different finish. Noordsman Diesel says BEB service is extended to 200,000km by using the race series bearings.
Mark at Diesels Unlimited in Perth recommends ARP studs at 25psi (at turbo) and over. I run 24 psi post intercooler at manifold ....so add in 2 to 3 psi pressure drop...I am over that. I guess I will bite the bullet.
Mark at Diesels Unlimited in Perth recommends ARP studs at 25psi (at turbo) and over. I run 24 psi post intercooler at manifold ....so add in 2 to 3 psi pressure drop...I am over that. I guess I will bite the bullet.
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- Thread starter
- #80
I have finally finished the bowl enlargement. I looked at a couple piston designs that are related to our 1HDT’s. I ended up shaping the lower lip similar to the marine 12 valve cummings design. I ground and shaped the square lower lip to a smooth transition.
Engine short block is assembled and in the Cruiser. Measured piston protrusion at between .030” to .032” so the 5 notch gasket. This is a little tighter than spec but I wanted to keep squish velocity and compression up as much as possible.
The head was flycut .010” previously. I chamfered the transition between the combustion chamber and valve pocket to aid flow at that point. I did this with the head assembled so it is not as smooth as I would like, but the square edge is gone with a 3 angle cut.
Waiting for the “direct fit ARP studs” to arrive to finish up the engine.
Set pump timing at .054" I think the manual was .051 to .053 so slightly advanced. I dont have the Cold Start device on my pump. I will adjust from there. Havent touched any fuel adjustments.
Below is a rough sketch of piston mods and some other misc pics of progress.
Engine short block is assembled and in the Cruiser. Measured piston protrusion at between .030” to .032” so the 5 notch gasket. This is a little tighter than spec but I wanted to keep squish velocity and compression up as much as possible.
The head was flycut .010” previously. I chamfered the transition between the combustion chamber and valve pocket to aid flow at that point. I did this with the head assembled so it is not as smooth as I would like, but the square edge is gone with a 3 angle cut.
Waiting for the “direct fit ARP studs” to arrive to finish up the engine.
Set pump timing at .054" I think the manual was .051 to .053 so slightly advanced. I dont have the Cold Start device on my pump. I will adjust from there. Havent touched any fuel adjustments.
Below is a rough sketch of piston mods and some other misc pics of progress.
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