Careless Posted July 7, 2007 Share Posted July 7, 2007 Hey everyone, Since I'm starting to get deep into the build now (only need pistons to be sorted out, really), I've not been able to come across the Dayco 94407 belt, or any of it's cross-reference counterparts from other manufacturers, such as Gates, Goodyear, and Bosch. I suspect the reason is because we never got the 1.7 liter diesel mazda engine that the belt was supplied for. (we, being the North American countries). What I've done was some sleuthing to get the proper belt here in west. And I've come up with some pretty good results, I'd say. I ended up buying a Gates PowerGrip GT2 1200-8MGT-30, which does not wrap around the crank sprocket drive gear properly. The teeth are not Trapezoidal or Modified Curvilinear, they are just Curvilinear, therefore they are too thick and don't allow the belt to fully circulate the gear or even 1/3 of it. Some reported that when tensioning the belt on, it will work. I have trouble believing that. And if it's true, I have trouble believing that it's going to last. HOWEVER, the belt in question is the strongest timing belt i've ever laid my hands on. It is VERY sturdy, amazingly well constructed, and like no belt I've ever seen, and the tooth profile seems as though it will be quiet as heck if it were to work. But, I don't feel comfortable using it just yet. And so begins my research. I found that most of the compatible belts are for volkswagen and audi 1.8T engines with designated engine code versions that differ slightly from others. On one engine, there is a belt with 153 teeth rather than the 152 required, or mostly used. I think this would still work if you positioned the tensioner in a slightly different position, however, I'll go with what's tested and has had fair results. What I've found is that the reason for volkswagen going from 152 teeth to 153 is due to the fact that their hydraulic tensioner they use starts to fail (did they take a page out of the Alfa 164S design schematics? lol) after a while and it starts to cause a lot of belt flap, and tooth shearing. They've since replaced the belt tensioner with a mechanical or better hydraulic version, and it requires a belt that has 1 more tooth, or is 8mm longer (measure from end to end of two teeth). And here are my belt part-number search results: BELT GUIDE FOR DOHC RB30 CONVERSIONS Upper Tensioner Relocation Method. Required Belt Length: 1216 mm Required Belt Width: 25 mm Required Tooth Pitch: 8mm Required Tooth Profile: Trapezoidal (prefered) or Modified Curvilinear Required Number of Teeth: 152 Compatible Belts: Gates T291 Goodyear Gatorback 40291 Bosch BT866 Dayco 94680 Dayco 94407 Continental Contitech CT919 (OEM volkswagen belt supplier) Factory Position - Dual Lower Tensioner Method. Required Belt Length: 1200 mm Required Belt Width: 23 to 25 mm Required Tooth Pitch: 8mm Required Tooth Profile: Trapezoidal (prefered) or Modified Curvilinear Required Number of Teeth: 150 Compatible Belts: Gates T306 Goodyear Gatorback 40306 Bosch BT306 Dayco 94777 Continental Contitech CT909 (OEM volkswagen belt supplier) Gates PowerGrip GT2 1200-8MGT-30 cut down to 25mm from 30mm at factory (Not Compatible, teeth must be ground down to proper depth, this is not safe and will not last very long, given the belt's woven structure!!!) This is a list of belts that i've compiled through comparing my new T291 belt to the stock SOHC dayco replacement belt for the RB30E. It fit exactly the same around the crank sprocket, so I did some sleuthing and cross referencing, and this is a list of belts that SHOULD be compatible. When I say SHOULD, I mean that someone mentioned the GT2 to be compatible, and it was not. These belts are in comparison to the level of compatibility shown by the GT2. Even if you've got a GT2 on your DE conversion, it most likely does not fit as well as these ones listed above do. Quote Link to comment Share on other sites More sharing options...
Stealth-Z Posted July 7, 2007 Share Posted July 7, 2007 You have been doing some homework! Mine will be using the Dayco 94407. Quote Link to comment Share on other sites More sharing options...
Careless Posted July 7, 2007 Author Share Posted July 7, 2007 You have been doing some homework! Mine will be using the Dayco 94407. yeah I couldn't get the Dayco, but I compared the Gates T291 with the Dayco belt that came with the RB30 that I have, it was left over from the SOHC head, and the tooth profile and pitch and belt thickness is EXACTLY the same, so being that it's the right size now, I am sure it will work. 99.9% sure it's the same as the dayco 94407 which is the same as the dayco 94680. I did this research because all the RB30 boards and threads were not being too helpful in regards to the belts, simply because they have access to most things over there, whereas we have to find work arounds. and the 8MGT-30 belt doesnt seem to fit, however some say it does. But I believe they are chatting up hearsay rather than experience.. which is common, but what I have here is research with some experimentation. It's understandable, though, and I don't blame anyone, simply because they have no need to find alternatives. So that's where I've come in. Time will tell, when it goes on the engine =) Quote Link to comment Share on other sites More sharing options...
bubbleguinea Posted July 7, 2007 Share Posted July 7, 2007 ill check the dayco number monday at work...i work at WDI and i can 96% probbaly get it for you for cheap... PM me and let me know, K? Quote Link to comment Share on other sites More sharing options...
AKWIKZ Posted July 7, 2007 Share Posted July 7, 2007 I managed to get the Wiseco situation sorted and have a set of pistons just sitting here. They are a 9.3:1 CR and are 1mm overbore. I don't have a real need for them anymore, so if you're interested I'd make you a good deal. Brian Quote Link to comment Share on other sites More sharing options...
Careless Posted July 8, 2007 Author Share Posted July 8, 2007 ill check the dayco number monday at work...i work at WDI and i can 96% probbaly get it for you for cheap... PM me and let me know, K? Oh don't worry about that. I got the T291 gates belt, and it looks like it's gonna work fine. Ideally, I'd like to have the gatorback belt, but I can't find anyone local who can get it. I'll try with this belt in about 2 months or so, when my RB26 gets here, and the time for compression calculation starts. Thanks for your help, though! It's why I love this Z Community Quote Link to comment Share on other sites More sharing options...
Careless Posted July 8, 2007 Author Share Posted July 8, 2007 I managed to get the Wiseco situation sorted and have a set of pistons just sitting here. They are a 9.3:1 CR and are 1mm overbore. I don't have a real need for them anymore, so if you're interested I'd make you a good deal. Brian im trying to get 11.25:1 lol i'd love to buy them from you for a good price, but i don't think they'd have enough dome height on them. they need 16cc atleast, or i'd need to chop the head quite a bit. then I would have to machine some reliefs in the pistons too =/ Quote Link to comment Share on other sites More sharing options...
Stealth-Z Posted July 8, 2007 Share Posted July 8, 2007 im trying to get 11.25:1lol i'd love to buy them from you for a good price, but i don't think they'd have enough dome height on them. they need 16cc atleast, or i'd need to chop the head quite a bit. then I would have to machine some reliefs in the pistons too =/ The pistons he has have a 16cc dome. I have another set identical to them except they are 0.020 oversized. Quote Link to comment Share on other sites More sharing options...
Careless Posted July 9, 2007 Author Share Posted July 9, 2007 what are the rest of the specs on the pistons. I will consider them if i can work with the CR by decking the head. I don't mind decking it a mm or more. Quote Link to comment Share on other sites More sharing options...
AKWIKZ Posted July 10, 2007 Share Posted July 10, 2007 Which specs do you need? Brian Quote Link to comment Share on other sites More sharing options...
Careless Posted July 10, 2007 Author Share Posted July 10, 2007 Which specs do you need? Brian Stealth-Z had emailed me regarding them already, however, I think if you're selling them, it's ok to post here: Compression height, overbore size if any, dome height, compression ratio on a RB30 or RB26 (whatever application they are originally for). basically what you request when ordering them (unless they're off the shelf) Quote Link to comment Share on other sites More sharing options...
Stealth-Z Posted July 11, 2007 Share Posted July 11, 2007 Stealth-Z had emailed me regarding them already, however, I think if you're selling them, it's ok to post here: Compression height, overbore size if any, dome height, compression ratio on a RB30 or RB26 (whatever application they are originally for). basically what you request when ordering them (unless they're off the shelf) These pistons are custom not off the shelf. No one to my knowledge has these specs with off the shelf items. Wiseco figures the pistons sit in the bore by about 0.020, RB26 head measures of 66cc's, and a stock head gasket at about 0.059. Once you start modifying those numbers, you will start to see different compression ratio's. These pistons will actually give me to high of a CR. Wiseco informed me it is okay to shave part of the dome off. Quote Link to comment Share on other sites More sharing options...
Careless Posted July 11, 2007 Author Share Posted July 11, 2007 These pistons are custom not off the shelf. No one to my knowledge has these specs with off the shelf items.Wiseco figures the pistons sit in the bore by about 0.020, RB26 head measures of 66cc's, and a stock head gasket at about 0.059. Once you start modifying those numbers, you will start to see different compression ratio's. These pistons will actually give me to high of a CR. Wiseco informed me it is okay to shave part of the dome off. woah woah. hold on. 66 cc? arias claims 64.5, and a lot of NZ doods claim 64 flat. ideally i'd need to drop my cc by 4 on the head side, and i could run into an 10.5 or so. I'm, going to go calc some more with dyno2003. Quote Link to comment Share on other sites More sharing options...
Stealth-Z Posted July 11, 2007 Share Posted July 11, 2007 woah woah. hold on. 66 cc? arias claims 64.5, and a lot of NZ doods claim 64 flat. ideally i'd need to drop my cc by 4 on the head side, and i could run into an 10.5 or so. I'm, going to go calc some more with dyno2003. Now you know why I measure myself. Look at Wiseco's catalog. Their Specs for RB26 head is 70cc's and the RB25 head is at 66.5cc's. http://www.wiseco.com/PDFs/Catalogs/SC07/NissanSubaruToyota.pdf My two RB26 heads measured out at 64cc's with light oil. Before the cutting, I am going to measure and do the math the old fashion way. The fancy computer calculator's all seem to be different. Quote Link to comment Share on other sites More sharing options...
Careless Posted July 11, 2007 Author Share Posted July 11, 2007 Now you know why I measure myself. Look at Wiseco's catalog. Their Specs for RB26 head is 70cc's and the RB25 head is at 66.5cc's.http://www.wiseco.com/PDFs/Catalogs/SC07/NissanSubaruToyota.pdf My two RB26 heads measured out at 64cc's with light oil. Before the cutting, I am going to measure and do the math the old fashion way. The fancy computer calculator's all seem to be different. i think they probably measure it with the headgasket on or something... either way it's dumb and/or rediculous. but apparently a lot of RB26 heads have differed. so who knows? I'm going to call my machinist tomorrow. Quote Link to comment Share on other sites More sharing options...
mjfawke Posted July 12, 2007 Share Posted July 12, 2007 Mate of mine did some consulting work with one of the belt manufacturers in Australia while building an RB30DET (they wanted to produce a kit for the RB30DET conversion) - turns out many of the belts people use for this conversion are not heat rated for the application, and will not have a good belt life. Something to consider... Quote Link to comment Share on other sites More sharing options...
Stealth-Z Posted July 12, 2007 Share Posted July 12, 2007 Mate of mine did some consulting work with one of the belt manufacturers in Australia while building an RB30DET (they wanted to produce a kit for the RB30DET conversion) - turns out many of the belts people use for this conversion are not heat rated for the application, and will not have a good belt life. Something to consider... Which belts are not properly heat rated? Quote Link to comment Share on other sites More sharing options...
Careless Posted July 12, 2007 Author Share Posted July 12, 2007 Mate of mine did some consulting work with one of the belt manufacturers in Australia while building an RB30DET (they wanted to produce a kit for the RB30DET conversion) - turns out many of the belts people use for this conversion are not heat rated for the application, and will not have a good belt life. Something to consider... JustJap.com has a Gates racing belt that they claim will work on the RB30DE + T, but upon emailing them and asking him if it was for the lower tensioner or the upper tensioner location, or if he could give me the Gates belt number to make sure which belt it was (closest is the T167RB, which is part of a set with the T168RB for the mitsubishi engines), he wouldn't cough it up. I understand, but atleast an indication of which location the tensioner should be in would be nice. However, I'm going to call gates myself when I put on my T291 belt. I'll see what kind of wear it goes through and then i'll judge whether or not I want to change it. The question about heat is in regards to friction from the tensioners. If you don't use TWO tensioners, you can't get the proper tension (too much), or you get too much slack. that would heat up the belt on the flat side (tight) or the tooth side (slack) and cause faster failures. something we got to solve, but I think we're ok for now. Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted July 14, 2007 Share Posted July 14, 2007 TB156YU29 That number should cross over. Quote Link to comment Share on other sites More sharing options...
Careless Posted July 15, 2007 Author Share Posted July 15, 2007 TB156YU29 That number should cross over. in google that belt comes up with only a PDF for a performance outlet for engine packages, and it is listed under a Mitsu Mirage 4G93T, which is a 1.8 litre DOHC. It uses, as a cross reference with gates and dayco, a 151 tooth 9.5mm pitch belt. That means that the teeth won't wrap around the crank drive gear properly, as it requires a 8mm pitch. It is also 1438mm long, the required length for a top tensioner mod is 1216mm long. Where did you get that number from? it doesnt even show up in their catalogue, which is why I had to do some more cross-ref to see if that's the correct belt. In all honesty, I'll sell the timing belt I have to someone from the VW crowd for 50 bucks flat, if I can get the proper racing belt. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.