# RB20det custom bore question **URL:** \ **Category:** SON240sx Automotive\ **Created:** [December 25, 2009, 11:14pm UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457 "2009-12-25T23:14:50Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![SRI\_Motorsports](https://avatars.discourse-cdn.com/v4/letter/s/e5b9ba/32.png) [@SRI\_Motorsports](https://forums.speedlife.net/u/SRI_Motorsports)\ **Post date:** [December 25, 2009, 11:14pm UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457/1 "2009-12-25T23:14:50Z")
Hey guys. As most of you know the rb20det is not really a desired motor over the 25 or 26. To me it is. I have a custom project going on and is still in the planning stages. This motor will be straight lined only. My stock bore is 78mm. The RB26 is same as the SR20 at 86mm. A RB26 head gasket is slightly different than the 20’s. The coolant passages are very slighty off. I can modify the block to allow the 26 gasket but is very time consuming and a tedious job. Does anyone have links or info for a head gasket manufacture to custom make one? Thanks for replies in advance. I;m sorry but I cant describe the build any further. One off motor being built with to many little secrets. Thanks again and merry christmas to you all. ---
**Author:** ![kollo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/kollo/32/5661_2.png) [@kollo](https://forums.speedlife.net/u/kollo)\ **Post date:** [December 26, 2009, 4:57am UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457/2 "2009-12-26T04:57:34Z")
there have been about 6 rb20 swaps done this year i`d say it`s a desired motor and it revs higher ---
**Author:** ![kix89](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/kix89/32/5689_2.png) [@kix89](https://forums.speedlife.net/u/kix89)\ **Post date:** [December 26, 2009, 5:49am UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457/3 "2009-12-26T05:49:52Z")
only m,otor i’d trade my rb20 in for, would be a 350ci ---
**Author:** ![Driftacular](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/driftacular/32/5724_2.png) [@Driftacular](https://forums.speedlife.net/u/Driftacular)\ **Post date:** [December 26, 2009, 9:40am UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457/4 "2009-12-26T09:40:53Z")
contact ARC240 on here or GTRC (better on gtrc) he built his 20 with a slightly larger bore, if anyone could help u …its him ---
**Author:** ![Wongger](https://avatars.discourse-cdn.com/v4/letter/w/41988e/32.png) [@Wongger](https://forums.speedlife.net/u/Wongger)\ **Post date:** [December 26, 2009, 11:36am UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457/5 "2009-12-26T11:36:24Z")
> [@where is your first car?](https://forums.speedlife.net/t/where-is-your-first-car/25435/12): > > Hey guys. As most of you know the rb20det is not really a desired motor over the 25 or 26. Ummmm? ---
**Author:** ![87s15lt1](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/87s15lt1/32/5706_2.png) [@87s15lt1](https://forums.speedlife.net/u/87s15lt1)\ **Post date:** [December 27, 2009, 11:19am UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457/6 "2009-12-27T11:19:38Z")
Cometic makes an 80 gasket. metal of course. ---
**Author:** ![DA\_1](https://avatars.discourse-cdn.com/v4/letter/d/ba8739/32.png) [@DA\_1](https://forums.speedlife.net/u/DA_1)\ **Post date:** [December 27, 2009, 9:13pm UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457/7 "2009-12-27T21:13:28Z")
> [@where is your first car?](https://forums.speedlife.net/t/where-is-your-first-car/25435/12): > > Hey guys. As most of you know the rb20det is not really a desired motor over the 25 or 26. To me it is. I have a custom project going on and is still in the planning stages. This motor will be straight lined only. My stock bore is 78mm. The RB26 is same as the SR20 at 86mm. A RB26 head gasket is slightly different than the 20’s. The coolant passages are very slighty off. I can modify the block to allow the 26 gasket but is very time consuming and a tedious job. Does anyone have links or info for a head gasket manufacture to custom make one? Thanks for replies in advance. I;m sorry but I cant describe the build any further. One off motor being built with to many little secrets. Thanks again and merry christmas to you all. It can be done but it wont be cheap…you will have to make up an actual jig and send it to a known gasket maker(cosmetic,felpro,etc) with ur EXACT specs I.E thickness,etc and they will make it just for you. will it be worth it in the long run bud!!! sure its nice to have a high revving motor,but weigh ALL ur pros n cons wisely. a high revving motor requires more maintainance and will NOT last as long as a bigger displacement motor.be prepared to run lots of NOS to make up for lost torque lol… the main question is at the end of the day will it be more capable than a rb26??? Hhmmm ---
**Author:** ![SRI\_Motorsports](https://avatars.discourse-cdn.com/v4/letter/s/e5b9ba/32.png) [@SRI\_Motorsports](https://forums.speedlife.net/u/SRI_Motorsports)\ **Post date:** [December 27, 2009, 9:29pm UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457/8 "2009-12-27T21:29:10Z")
I understand my friend. The 26 will get rocked. Again we will talk about the components used at a later date. It will out power and beat the torque of a stock 26 on same psi. Trust me. You will think I am crazy. You know what…I will call you tomorrow evening and let you in on the build. You will understand after that. After all you and 2 other people I trust with this information. Thanks for the response about the gasket by the way. I called around and got that info just a few days ago. ---
**Author:** ![DA\_1](https://avatars.discourse-cdn.com/v4/letter/d/ba8739/32.png) [@DA\_1](https://forums.speedlife.net/u/DA_1)\ **Post date:** [December 27, 2009, 9:32pm UTC](https://forums.speedlife.net/t/rb20det-custom-bore-question/130457/9 "2009-12-27T21:32:12Z")
nice